Chungking mansions have gone now i believe, its was the pits of Nathan rd,rat infested hovel.
Stayed there one night in travellers hostel long time ago on top floor, window was open during the night, and you could see the rats walkway going up and down the building, no need to count sheep to get to sleep.
A guy who stayed there on a regular basis told us stories of rats coming up the toilet when people where having craps.