This photo shows the old Causeway Bay Typhoon shelter.
It's attributed to 1962, but the date should be 1955 or 1956. The Typhoon shelter was reclamed 1956/57 to become Victoria Park (opened 1957). Date confirmed. see David's comment below.
The rounded house right hand side on the hill (at the bend of Tai Hang Road) is Grandview Mansion, first occupied 1/1955.
Below it, a house on a round structure is under construction, probably built on the site of the mystery building.