Angkor Thom: Baphûon

Baphûon was built around 1060, under the reign of Udayādityavarman II (who reigned from 1050 to 1066), to the glory of Shiva. There was once the state temple, known as the "golden mountain" (svarnādrī).

It stood on top of an artificial hill, but had almost disappeared before being cleared and consolidated in several stages from 1908 to 1918. Major landslides forced the consolidation to resume in 1950. It is assumed that it was once entirely covered with bronze plaques, in order to make the artificial hill look like Mount Meru.

Invaded by vegetation, it has been undergoing restoration since 1995, in a project supported by the EFEO, under the aegis of architects Jacques Dumarçay and Pascal Royère. This temple has the particularity of having undergone a major overhaul (much later than its construction)

Access to the temple is currently (June 2010) very limited,
given the importance of the restoration work.

Further explanations here:

More on Wikipedia