The Potala Palace in Lhasa is a UNESCO World Heritage since 1994 and was built in several construction phases. The palace construction began in 637 by Songtsen Gampo, the king in Tibet at that time. The building was a present for his bride Princess Wen Cheng of the Chinese Tang Dynasty. In the 17th century the palace was integrated in a bigger construction. At the beginning of the 20th century the last important structural measures took place. Today the palace is used as a museum and among the Tibetan Buddhists it is considered an important pilgrimage site.