Cambodiana Hotel

The construction of the building that was to become the Cambodiana Hotel began in the late 1960s but was interrupted by the war that began in 1970. It became a military barracks during the Lon Nol era and was subsequently abandoned after 1975. In 1988 Singaporean investors re-launched the project and completed the construction. It was first opened as a hotel in June 1990. Many diplomats and journalists stayed there during the 1991-93 UNTAC period. It is now run by the Royal Group. 

The picture shows a large body of water to the south of the hotel, which has long since been reclaimed land. You might also notice the rows of cottage like buildings in the triangular park between Sisowath and St 258, and further north the houses along the quay north of the palace where there is now a riverside park. The park at Wat Botum is much larger too, you can see a lot of trees around where the Bodyguard HQ is now.
I'd guess this picture was taken around 1989 as the hotel looks almost complete other than the front grounds. There was a water sport complex which briefly became a casino in the late 60's in the area to the south, but the water is now part of Hun Sen Park and the Dreamland amusement park.