Ask for a bus (mini-busI to the Old Town (Stary Bar). If the time is inconvenient, take a bus to Ulcinj and ask the driver to stop at Posta Celuga (read "Tseluga") and Vladra cafe. Cross the road and go towards a mosque (that's North-East from the road). You will already see the fortress. It's a walk of less then two kilometers (if there is a taxi near the post office / Kaca shop, take it but do not forget to bargain. Actually, the bus station is also not far away: just a little more then 2 km from it to Posta Celuga, so the whole distance is walkable and a taxi will not be really expensive (4 km). Rent a bike which is a good option. Get to roundabout North-East from bus station, just beyond crossing with railway, then past "Pero Cetkovic" military barracks, leaving them to the left; and then walk or drive straight in the Ulcinj direction to the Posta Celuga and other places mentioned above. Road to the Old Town is just beyonf Vladra cafe.