1.The Potala Palace: Tibet's greatest monumental structure

Perched upon Marpo Ri hill, 130 meters above the Lhasa valley, the Potala Palace rises a further 170 meters and is the greatest monumental structure in all of Tibet. In 637 Emperor Songtsen Gampo decided to build this palace on a hill, and the structure stood until the seventeenth century, when it was incorporated into the foundations of the greater buildings still standing today. Construction of the present palace began in 1645 during the reign of the fifth Dalai Lama and by 1648 the Potrang Karpo, or White Palace, was completed. The Potrang Marpo, or Red Palace, was added between 1690 and 1694; its construction required the labors of more than 7000 workers and 1500 artists and craftsman. The Potala Palace was only slightly damaged during the Tibetan uprising against the invading Chinese in 1959. Unlike most other Tibetan religious structures, it was not sacked by the Red Guards during the 1960s and 1970s. As a result, all the chapels and their artifacts are very well preserved.

2.Mont Saint-Michel: a Medieval Castle on a Small Island

Mont St Michel France is situated on a quasi-island on the Normandy coast, near Brittany, which at high tide is almost entirely separated from the mainland. Only a narrow causeway, constructed in the 1880s preserves a link to the coast. Beware: the tide comes in quickly - many tourists have drowned attempting to cross the sandy bay. Unlike other castles in France, which began as defensive structures or pleasure palaces, Mont St Michel had its beginnings as a monastery. Today, the Castle attracts over four million visitors a year, far more than most castles in France and has been featured in numerous movies, cartoons, and even videogames.

3.Predjamski Castle: Integrated in a Cave

Every castle in the world is unique in some way, no two are the same, but this one —even though it's rather small and humble compared to some— is probably the only one in the world who is integrated in a cave, precisely the second largest cave system in Slovenia. Its name, Predjamski Grad, literally means "Castle in Front of the Cave."

4.Neuschwanstein Castle: the Classic Fairytale's Castle

The most famous of three royal palaces built for Louis II of Bavaria, sometimes referred to as Mad King Ludwig, the Neuschwanstein it's a royal palace in the Bavarian Alps of Germany. egun in 1869 and left unfinished at Louis's death in 1886, the castle is the embodiment of 19th century romanticism. In a fantastical imitation of a medieval castle, Neuschwanstein is set with towers and spires and is spectacularly sited on a high point over the Pullat River gorge.

5.Matsumoto Castle: Japan's most fascinating castle

Matsumoto Castle, locally known as Matsumotojo, is one of the most complete and beautiful among Japan's original castles. It is also a good example of a so called "hirajiro", a castle built on the plain rather than on a hill or mountain. Matsumotojo's castle tower and smaller, second turret were built from 1592 to 1614 and were both well defended, as peace was not yet fully secured at the time. In 1635, when no more military threats existed, a third, barely defended turret for moon viewing was added to the castle.