Although facilities are improving in St Petersburg, travelers with disabilities, especially those in wheelchairs, are likely to encounter some difficulties. Most churches and museums have no wheelchair access, although the Hermitage and the Russian Museum are honorable exceptions.
Public transport is also problematic, with no wheelchair access to buses or trams, and no elevator service on the metro. Also, bear in mind that stops are far apart, especially in the suburbs, so if your walking capabilities are limited be sure to check distances in advance.
You should also always call ahead to find out if there is wheelchair access to bars, clubs and restaurants. In the majority of cases the answer, sadly, will be in the negative.