Stack's hotel is called the Paloma Hotel but we're not told where it is. However, a quick bit of investigation shows that it is most likely Kimberley Road thanks to the sign on the outside of the building that shows its real name - although it's only at a later point in the film when this is revealed (see the bottom picture). The Luna Building: 月仙樓.
This grand old building doesn't exist anymore and it's replacement, Luna Court, a modern residential unit, was built in 1988. More interestingly is the row of tenements on the other side of the road because a couple of these still stand today at 42-44 and 50-52 Kimberley Road.