10 most difficult sky­scrapers riddles

Designed by the French structural engineer Michel Virlogeux and British architect Norman Foster, it is the tallest bridge in the world. The P2 pier of the Viaduct is 343.0 meters (1,125 ft) tall, 19 meters taller than the Eiffel tower.

The Empire State Building took only one year and 45 days to build, or 7 million man-hours. To this day, this is a record for a skyscraper of its height. Due to reduced costs during the Depression, the final costs totalled only $24.7 million instead of the estimated $43 million.

Although the tower no longer serves as the Transamerica Corporation headquarters, it is still strongly associated with the company and is depicted in the company's logo. In 1999, Transamerica was acquired by Dutch insurance company Aegon. When the non-insurance operations of Transamerica were later sold to GE Capital, Aegon retained the building as an investment

Samsung C&T Corporation (Construction and Trade), established in 1938, is the origin of Samsung Group. Samsung C&T was the primary contractor of 3 worlds tallest skyscrapers: Burj Khalifa, Petronas Twin Towers and Taipei 101.

In 2012, seven of the fifteen tallest skyscrapers in Europe were located in Moscow. There are also several high-rise buildings under construction there.

Hong Kong lost its leadership to Dubai if only high-rise skyscrapers above 300m are counted. But in category "over 100m", its position is safe with over 2300 buildings. It is followed by New York City with less than 800.

The Santa Justa Lift connects the lower streets of the Baixa with the higher Carmo Square. Since its construction, the Lift has become a tourist attraction in Lisbon. Among the urban lifts in the city, Santa Justa is the only remaining vertical one.

Tokyo Skytree (pictured) reached its full height of 634.0 meters (2,080 ft) in March 2011, making it the tallest tower in the world, displacing the Canton Tower, and the second tallest structure in the world.

The Sky Tower in Auckland (pictured) is 328 meters or 1,076 ft tall. It has become an iconic structure in Auckland's skyline.

The construction lasted only one year and 35 days. Designed by Shreve, Lamb & Harmon, the building has a roof height of 380 m, and with its antenna included, it stands a total of 443.2 m tall. Its name is derived from "Empire State", the nickname for New York. As of 2017 the Empire State Building is the fifth-tallest completed skyscraper in the United States and the 28th-tallest in the world.