Howrah Bridge

Howrah Bridge

Howrah Bridge is a bridge with a suspended span over the Hooghly River in West Bengal, India. Commissioned in 1943, the bridge was originally named the New Howrah Bridge, because it replaced a pontoon bridge at the same location linking the two cities of Howrah and Kolkata (Calcutta). On 14 June 1965 it was renamed Rabindra Setu after the great Bengalipoet Rabindranath Tagore, who was the first Indian and Asian Nobel laureate.^[10] It is still popularly known as the Howrah Bridge.

The bridge is one of four on the Hooghly River and is a famous symbol of Kolkata and West Bengal. The other bridges are the Vidyasagar Setu (popularly called the Second Hooghly Bridge), the Vivekananda Setu, and the newly built Nivedita Setu. It weathers the storms of the Bay of Bengal region, carrying a daily traffic of approximately 100,000 vehicles and possibly more than 150,000 pedestrians,easily making it the busiest cantilever bridge in the world. The third-longest cantilever bridge at the time of its construction, the Howrah Bridge is currently the sixth-longest bridge of its type in the world.

Construction

The bridge does not have nuts and bolts, but was formed by riveting the whole structure. It consumed 26,500 tons of steel, out of which 23,000 tons of high-tensile alloy steel, known as Tiscrom, were supplied by Tata Steel. The main tower was constructed with single monolith caissons of dimensions 55.31 x 24.8 m with 21 shafts, each 6.25 metre square. The Chief Engineer of the Port Trust, Mr. J. McGlashan, wanted to replace the pontoon bridge, with a permanent structure, as the present bridge interfered with North/South river traffic. Work could not be started as World War I (1914-1918) broke out. Then in 1926 a commission under the Chairmanship of Sir R. N. Mukherjee recommended a suspension bridge of a particular type to be built across the River Hoogly. The bridge was designed by one Mr.Walton of M/s Rendel, Palmer & Triton. The order for construction and erection was placed on M/s.Cleveland Bridge & Engineering Company in 1939. Again World War II (1939-1945 ) intervened. All the steel that was to come from England were diverted for war effort in Europe. Out of 26,000 tons of steel, that was required for the bridge, only 3000 tons were supplied from England. In spite of the Japanese threat, the then (British) government of India pressed on with the construction. Tata Steel were asked to supply the remaining 23,000 tons of high tension steel. The Tatas developed the quality of steel required for the bridge and called it Tiscom. The entire 23,000 tons was supplied in time. The fabrication and erection work was awarded to a local engineering firm of Howrah: the Braithwaite, Burn & Jessop Construction Co.. The two anchorage caissons were each 16.4 m by 8.2 m, with two wells 4.9 m square. The caissons were so designed that the working chambers within the shafts could be temporarily enclosed by steel diaphragms to allow work under compressed air if required. The caisson at Kolkata side was set at 31.41 m and that at Howrah side at 26.53 m below ground level.

One night, during the process of grabbing out the muck to enable the caisson to move, the ground below it yielded, and the entire mass plunged two feet, shaking the ground. The impact of this was so intense that the seismograph at Kidderporeregistered it as an earthquake and a Hindu temple on the shore was destroyed, although it was subsequently rebuilt. While muck was being cleared, numerous varieties of objects were brought up, including anchors, grappling irons, cannons, cannonballs, brass vessels, and coins dating back to the East India Company. The job of sinking the caissons was carried out round-the-clock at a rate of a foot or more per day. The caissons were sunk through soft river deposits to a stiff yellow clay 26.5 m below ground level. The accuracy of sinking the huge caissons was exceptionally precise, within 50–75 mm of the true position. After penetrating 2.1 m into clay, all shafts were plugged with concrete after individual dewatering, with some 5 m of backfilling in adjacent shafts.^[20] The main piers on the Howrah side were sunk by open wheel dredging, while those on the Kolkata side required compressed air to counter running sand. The air pressure maintained was about 40 lbs per square inch (2.8 bar), which required about 500 workers to be employed.^[12] Whenever excessively soft soil was encountered, the shafts symmetrical to the caisson axes were left unexcavated to allow strict control. In very stiff clays, a large number of the internal wells were completely undercut, allowing the whole weight of the caisson to be carried by the outside skin friction and the bearing under the external wall. Skin friction on the outside of the monolith walls was estimated at 29 kN/m² while loads on the cutting edge in clay overlying the founding stratum reached 100 tonnes/m. The work on the foundation was completed on November 1938.

By the end of 1940, the erection of the cantilevered arms was commenced and was completed in mid-summer of 1941. The two halves of the suspended span, each 282 feet (86 m) long and weighing 2,000 tons, were built in December 1941. The bridge was erected by commencing at the two anchor spans and advancing towards the center, with the use of creeper cranes moving along the upper chord. 16 hydraulic jacks, each of which had an 800-ton capacity, were pressed into service to join the two halves of the suspended span.

The entire project cost ₹25 million (£2,463,887). The project was a pioneer in bridge construction, particularly in India, but the government did not have a formal opening of the bridge due to fears of attacks by Japanese planes fighting the Allied Powers. Japan had attacked the United States at Pearl Harbor on December 7, 1941. The first vehicle to use the bridge was a solitary tram.

The bridge is regarded "the gateway to Kolkata, as it connects the city to the Howrah Station".

The Howrah Bridge
Coordinates	22.5851°N 88.3469°E
Carries	4 lanes[1] of Strand Road,[2] pedestrians and bicycles
Crosses	Hooghly River
Locale	Howrah and Kolkata
Official name	Rabindra Setu
Maintained by	Kolkata Port Trust[3]
Characteristics
Design	Suspension type Balanced Cantilever[4]and truss arch[5]
Material	Steel
Total length	705 m (2,313.0 ft)[6][7]
Width	71 ft (21.6 m) with two footpaths of 15 ft (4.6 m) on either side[4]
Height	82 m (269.0 ft)[5]
Longest span	1,500 ft (457.2 m)[4][5]
Clearance above	5.8 m (19.0 ft)[4]
Clearance below	8.8 m (28.9 ft)[4]
History
Designer	Rendel, Palmer and Tritton[8]
Constructed by	Braithwaite, Burn & Jessop Construction
Construction start	1936[8]
Construction end	1942[8]
Opened	3 Feb 1943; 75 years ago[7]
Statistics
Daily traffic	100,000 vehicles and 150,000 pedestrians[9]
Toll	Free both ways
Howrah Bridge Location in West Bengal

Petra

Petra

Petra (Arabic: البتراء, Al-Batrāʾ; Ancient Greek: Πέτρα), originally known to its inhabitants as Raqmu, is a historical and archaeological city in southern Jordan. Petra lies on the slope of Jabal Al-Madbah in a basin among the mountains which form the eastern flank of Arabah valley that run from the Dead Sea to the Gulf of Aqaba. According to Hieronymus of Cardia, the name "Petra" was given by Greek merchants, who observed the city's inhabitants offering sacrifice, in springtime, to a deity on a large stone, i.e. petra. Petra is believed to have been settled as early as 9,000 BC, and it was possibly established in the 4th century BC as the capital city of the Nabataean Kingdom. The Nabataeans were nomadic Arabswho invested in Petra's proximity to the trade routes by establishing it as a major regional trading hub.

The trading business gained the Nabataeans considerable revenue and Petra became the focus of their wealth. The earliest historical reference to Petra was the attack to the city ordered by Antigonus I in 312 BC recorded by various Greek historians. The Nabataeans were, unlike their enemies, accustomed to living in the barren deserts, and were able to repel attacks by utilizing the area's mountainous terrain. They were particularly skillful in harvesting rainwater, agriculture and stone carving. Most of the Nabataean rulers embraced Greek culture, first of which was Aretas III Philhellen (87-62 BC), up to the last Nabataean ruler, Rabbel II Soter (70-106 AD). Petra flourished in the 1st century AD when its famous Khazneh structure –believed to be the mausoleum of Nabataean King Aretas IV– was constructed using Greek architectural elements, and its population peaked at an estimated 20,000 inhabitants.

Although the Nabataean Kingdom became a client state for the Roman Empire in the first century BC, it was only in 106 AD that they lost their independence. Petra fell to the Romans who annexed and renamed Nabataea to Arabia Petraea. Petra's importance declined as sea trade routes emerged, and after a 363 earthquake destroyed many structures. The Byzantine Era witnessed the construction of several Christian churches, but the city started to decline after attacks due to the emerging Sasanid Empire, and by the early Islamic era became an abandoned place where only a handful of nomads lived. It remained unknown to the world until it was rediscovered in 1812 by Johann Ludwig Burckhardt.

The city is accessed through a 1.2 kilometres (0.75 mi) long gorge called the Siq, which leads directly to the Khazneh. Famous for its rock-cut architecture and water conduit system, Petra is also called the Rose City due to the color of the stone out of which it is carved. It has been a UNESCO World Heritage Site since 1985. UNESCO has described it as "one of the most precious cultural properties of man's cultural heritage". In 2007, Al-Khazneh was voted in as one of the New7Wonders of the World. Petra is a symbol of Jordan, as well as Jordan's most-visited tourist attraction. Tourist numbers peaked at 1 million in 2010, the following period witnessed a slump due to regional instability. However, tourist numbers have picked up recently, and around 600,000 tourists visited the site in 2017.

Location	Ma'an Governorate, Jordan
Coordinates	30°19′43″N 35°26′31″ECoordinates: 30°19′43″N 35°26′31″E
Area	264 square kilometres (102 sq mi)[1]
Elevation	810 m (2,657 ft)
Built	possibly as early as 5th century BC [2]
Visitors	596,602 (in 2014)
Governing body	Petra Region Authority
Website	www.visitpetra.jo

Colosseum

Colosseum

Colosseum is situated just east of the Roman Forum. Construction began under the emperor Vespasian in AD 72, and was completed in AD 80 under his successor and heir Titus.^[3]Further modifications were made during the reign of Domitian (81–96). These three emperors are known as the Flavian dynasty, and the amphitheatre was named in Latinfor its association with their family name (Flavius).

The Colosseum could hold, it is estimated, between 50,000 and 80,000 spectators, having an average audience of some 65,000; it was used for gladiatorial contests and public spectacles such as mock sea battles (for only a short time as the hypogeumwas soon filled in with mechanisms to support the other activities), animal hunts, executions, re-enactments of famous battles, and dramas based on Classical mythology. The building ceased to be used for entertainment in the early medievalera. It was later reused for such purposes as housing, workshops, quarters for a religious order, a fortress, a quarry, and a Christian shrine.

Although partially ruined because of damage caused by earthquakes and stone-robbers, the Colosseum is still an iconic symbol of Imperial Rome and is listed as one of the New7Wonders of the World. It is one of Rome's most popular tourist attractions and also has links to the Roman Catholic Church, as each Good Fridaythe Pope leads a torchlit "Way of the Cross" procession that starts in the area around the Colosseum.

Location	Regio IV Templum Pacis ("Temple of Peace")
Built in	70–80 AD
Built by/for	Vespasian, Titus
Type of structure	Amphitheatre
Related	List of ancient monuments in Rome

Forbidden City

 Forbidden City

The Forbidden City is a palacecomplex in central Beijing, China. The former Chinese imperial palace from the Ming dynasty to the end of the Qing dynasty (the years 1420 to 1912), it now houses the Palace Museum. The Forbidden City served as the home of emperors and their households as well as the ceremonial and political center of Chinese government for almost 500 years.

Constructed from 1406 to 1420, the complex consists of 980 buildingsand covers 72 hectares (over 180 acres). The palace exemplifies traditional Chinese palatial architecture and has influenced cultural and architectural developments in East Asia and elsewhere. The Forbidden City was declared a World Heritage Site in 1987, and is listed by UNESCO as the largest collection of preserved ancient wooden structures in the world.

Since 1925, the Forbidden City has been under the charge of the Palace Museum, whose extensive collection of artwork and artifacts were built upon the imperial collections of the Ming and Qing dynasties. Part of the museum's former collection is now in the National Palace Museum in Taipei. Both museums descend from the same institution, but were split after the Chinese Civil War. Since 2012, the Forbidden City has seen an average of 15 million visitors annually, and received more than 16 million visitors in 2016 and 2017.

Established	1925
Location	4 Jingshan Front St, Dongcheng, Beijing, China
Coordinates	39.915987°N 116.397925°ECoordinates: 39.915987°N 116.397925°E
Type	Art museum, Imperial Palace, Historic site
Visitors	16.7 million[1] Ranking 1st globally
Curator	Shan Jixiang (单霁翔)
Built	1406–1420
Architect	Kuai Xiang
Architectural style(s)	Chinese architecture
Website	en.dpm.org.cn (English language version) www.dpm.org.cn (Chinese language version)
UNESCO World Heritage site
Part of	Imperial Palaces of the Ming and Qing Dynasties in Beijing and Shenyang
Criteria	Cultural: i, ii, iii, iv
Reference	439-001
Inscription	1987 (11th Session)

Machu Picchu

Machu Picchu

The site is roughly divided into an urban sector and an agricultural sector, and into an upper town and a lower town. The temples are in the upper town, the warehouses in the lower.

The architecture is adapted to the mountains. Approximately 200 buildings are arranged on wide parallel terraces around an east-west central square. The various compounds, called kanchas, are long and narrow in order to exploit the terrain. Sophisticated channeling systems provided irrigation for the fields. Stone stairways set in the walls allowed access to the different levels across the site. The eastern section of the city was probably residential. The western, separated by the square, was for religious and ceremonial purposes. This section contains the Torreón, the massive tower which may have been used as an observatory.

Located in the first zone are the primary archaeological treasures: the Intihuatana, the Temple of the Sun and the Room of the Three Windows. These were dedicated to Inti, their sun god and greatest deity.

The Popular District, or Residential District, is the place where the lower-class people lived. It includes storage buildings and simple houses.

The royalty area, a sector for the nobility, is a group of houses located in rows over a slope; the residence of the amautas (wise persons) was characterized by its reddish walls, and the zone of the ñustas (princesses) had trapezoid-shaped rooms. The Monumental Mausoleum is a carved statue with a vaulted interior and carved drawings. It was used for rites or sacrifices.

The Guardhouse is a three-sided building, with one of its long sides opening onto the Terrace of the Ceremonial Rock. The three-sided style of Inca architecture is known as the wayrona style.

In 2005 and 2009, the University of Arkansas made detailed laser scans of the entire site and of the ruins at the top of the adjacent Huayna Picchu mountain. The scan data is available online for research purposes.

Location	Cuzco Region, Peru
Coordinates	13°09′48″S 72°32′44″WCoordinates: 13°09′48″S 72°32′44″W
Height	2,430 metres (7,970 ft)
History
Founded	c. 1450
Abandoned	1572
Cultures	Inca civilization
Site notes
Archaeologists	Hiram Bingham
UNESCO World Heritage Site
Official name	Historic Sanctuary of Machu Picchu
Type	Mixed
Criteria	i, iii, vii, ix
Designated	1983 (7th session)
Reference no.	274
State Party	Peru
Region	Latin America and the Caribbean

Great Wall of China

Great Wall of China

The Great Wall of China is a series of fortifications made of stone, brick, tamped earth, wood, and other materials, generally built along an east-to-west line across the historical northern borders of China to protect the Chinese states and empiresagainst the raids and invasions of the various nomadic groups of the Eurasian Steppe with an eye to expansion. Several walls were being built as early as the 7th century BC; these, later joined together and made bigger and stronger, are collectively referred to as the Great Wall.Especially famous is the wall built in 220–206 BC by Qin Shi Huang, the first Emperor of China. Little of that wall remains. The Great Wall has been rebuilt, maintained, and enhanced over various dynasties; the majority of the existing wall is from the Ming Dynasty (1368–1644).

Apart from defense, other purposes of the Great Wall have included border controls, allowing the imposition of duties on goods transported along the Silk Road, regulation or encouragement of trade and the control of immigration and emigration. Furthermore, the defensive characteristics of the Great Wall were enhanced by the construction of watch towers, troop barracks, garrison stations, signaling capabilities through the means of smoke or fire, and the fact that the path of the Great Wall also served as a transportation corridor.

The frontier walls built by different dynasties have multiple courses. Collectively, they stretch from Dandong in the east to Lop Lake in the west, from present-day Sino-Russian border in the north to Qinghai in the south; along an arc that roughly delineates the edge of Mongolian steppe. A comprehensive archaeological survey, using advanced technologies, has concluded that the walls built by the Ming dynasty measure 8,850 km (5,500 mi). This is made up of 6,259 km (3,889 mi) sections of actual wall, 359 km (223 mi) of trenches and 2,232 km (1,387 mi) of natural defensive barriers such as hills and rivers. Another archaeological survey found that the entire wall with all of its branches measures out to be 21,196 km (13,171 mi). Today, the Great Wall is generally recognized as one of the most impressive architectural feats in history.

General information
Type	Fortification
Country	China
Coordinates	40.68°N 117.23°EE
Technical details
Size	21,196 km (13,171 mi)[1]
UNESCO World Heritage Site
Official name	The Great Wall
Type	Cultural
Criteria	i, ii, iii, iv, vi
Designated	1987 (11th session)
Reference no.	438
State Party	China
Region	Asia-Pacific