10 most difficult land­marks riddles

The convent was ruined in the 1755 Great Lisbon Earthquake, which destroyed the city, killed possibly 100.000 of its inhabitants and disrupted the colonial ambitions of Portugal. The church was left unrestored to remind the tragedy.

The Potala Palace in Lhasa, was the chief residence of the Dalai Lama until the 14th Dalai Lama fled to Dharamsala, India, during the 1959 Tibetan uprising. Today, the Potala Palace is a museum.

The three pyramids were built by pharaons of the fourth dynasty: Khufu, his son Khafre and Kahafre's son, Menkaure. Today, they are better known by their hellenized names: Cheops, Chephren and Mykerinos. Along with these major monuments are a number of smaller satellite edifices, known as "queens" pyramids.

Mount Nemrut is a 2,134 m (7,001 ft) high mountain in southeastern Turkey. Near the summit, a number of large statues of Greek and Iranian gods are erected around the royal tomb, which King Antiochus I Theos of Commagene built for himself in 62 BC. The heads of the statues have at some stage been removed from their bodies, and they are now scattered throughout the site.

After the 1806 Prussian defeat, Napoleon was the first to use the Brandenburg Gate for a triumphal procession and took the Quadriga to Paris. It was restored in 1814, after Napoleon's defeat and the Prussian occupation of Paris.

The Colosseum was built by the three emperors known as the Flavian dynasty (Vespasian, Titus, Domitian). During the Ancient times, it was known in Latin as Amphitheatrum Flavium. The name "Colosseum" had been coined to refer to the amphitheatre around year 1000 AD.

The Gateway Arch is a 630-foot (192 m) monument in St. Louis, Missouri. It was built as a monument to the westward expansion of the United States, it is the centerpiece of the Jefferson National Expansion Memorial and has become an internationally famous symbol of St. Louis. It is the tallest man-made monument in the United States and the world's tallest arch.

Yosemite National Park lies in the western Sierra Nevada of California. Designated a World Heritage Site in 1984, Yosemite is internationally recognized for its granite cliffs, waterfalls, clear streams, giant sequoia groves, lakes, mountains, meadows, glaciers, and biological diversity. Almost 95% of the park is designated wilderness.

One of the most admired works of contemporary architecture, The Guggenheim Museum Bilbao was opened in 1997. Computer simulations of the building's structure made it feasible to build shapes that architects of earlier eras would have found nearly impossible to construct

The Pinnacles are limestone formations contained within the Nambung National Park, near the town of Cervantes in Western Australia. Three different mechanisms have been proposed to explain the way the pinnacles were formed.