Potala Palace is the most famous monumental structure of Tibet. The complex comprising the White and Red Palaces with their ancillary buildings is built on Marpo Ri in the centre of Lhasa Valley at an altitude of 3700m. Thirteen storeys of buildings soaring 117 m. above the valley level covers an area of over 130000 sq. metres and stands majestically 110 m. high. Construction of the Potala Palace began in 7th century AD during the reign of Choegyal Songtsen Gampo. It was rebuilt in the mid-17th century by His Holiness the Fifth Dalai Lama and reached its present size as a result of repeated renovation and expansion over the centuries