Hi Clare
I went to the one at Burgas on a shopping trip booked in resort,you go to the Metro and then on to Burgas and finally stop at the gypsy market on the way back.The problem with that is you dont get a lot of time to look around,so we took a taxi the next time we went.
You have to take your passport with you so they can check your identity and they issue you with a day pass.
It might be different now as this was two year ago.
Basil.