A Pakistani labourer carries bricks on his back at a construction site at a residential area in Islamabad on March 29, 2017. (Photo by Aamir Qureshi/AFP Photo)
Construction work on the tower began in November 2008. Upon its completion this year the building will stand approximately 632 meters (2,073 ft.) high and will have 121 stories. It is expected to open to the public in 2015. (Photo by Rex Features)
Two men standing on a high catwalk, surveying the construction of the Brooklyn Bridge, with Manhattan in the background, New York City, 1877. (Photo by Museum of the City of New York/Archive Photos/Getty Images)