Art Dealers key
Another way to get this Key is to help the Art Dealer Ex-Maid. Save her from the 2 Guards at the Alley beside the First and Second Wall of Light. Approach her after saving her by killing off the 2 guards or putting them to sleep. She will reward you with the Art Dealer's Apartment Key.
House of Pleasure
Art Dealer's Safe Combination Needed
The safe combination is chosen at random . Trying each combination below will grant you access eventually:
616 Just enter any 3 digit code. The door is broke.