I have kept bees for three years on my fourth floor residence on a deck.  The
bees are thriving!  The neighbors did not even know the two hives were there
until I gave them all a pound of honey after the first harvest (110 pounds).
 
The urban honey is delicious, it being derived from a variety of city
sources--much more interesting and delicious than that boring single source
stuff.
 
Go for it!