The Pretty Woman star was 'astonished' with the grandeur of the so-called temple mountain, which lies between two volcanoes about 40km north-west of Yogyakarta.
One of the peaks, Merapi, killed more than 320 people last year in its biggest eruption in over a century.
The temple was abandoned with the spread of Islam on Java island in the 14th century, but was 'rediscovered' in 1814 by English trader Sir Thomas Stamford Raffles.
Restored with the help of Unesco in the 1970s, it is now Indonesia's most-visited tourist attraction, drawing about 3.8 million people last year.