The site was visited by the American linguist
A. V. Williams Jackson in 1903. Later expeditions, in 1904 sponsored by the
British Museum and led by
Leonard William King and
Reginald Campbell Thompson and in 1948 by George G. Cameron of the
University of Michigan, obtained photographs, casts and more accurate transcriptions of the texts, including passages that were not copied by Rawlinson. It also became apparent that rainwater had dissolved some areas of the limestone in which the text was inscribed, while leaving new deposits of limestone over other areas, covering the text. In 1938, the inscription became of interest to the Nazi German think tank
Ahnenerbe, although research plans were cancelled due to the onset of World War II. The monument later suffered some damage from
Allied soldiers using it for target practice in
World War II, and during the
Anglo-Soviet invasion of Iran. In 1999, Iranian archeologists began the documentation and assessment of damages to the site incurred during the 20th century. Malieh Mehdiabadi, who was
project manager for the effort, described a
photogrammetric process by which two-dimensional photos were taken of the inscriptions using two cameras and later transmuted into 3-D images. In recent years, Iranian archaeologists have been undertaking conservation works. The site became a UNESCO
World Heritage Site in 2006. In 2012, the Bisotun Cultural Heritage Center organized an international effort to re-examine the inscription. ==Content==