I will also chime in here and say (just for fun) that
- what sometimes looks to be city owned property is sometimes not
- what sometimes is city property are 'paper' alleys (ie never built) and require a trip to the DC Council for any sort of ownership transfer
- utilities are usually the showstopper for these sorts of inquiries. very, very spendy to put them in.
- and if that's not enough, if it's truly an 'alley lot', they have their own 'special' set of zoning rules.
Generally, none of this orphan land stuff is neither straightforward nor obvious. Not for the faint of heart. However, it never hurts to start asking the questions. You never know where you'll end up.
Tanya