Know Before You Go
You can travel to the city of Vidin from Sofia by bus (4 hours) or train (5 hours). Many Danube River cruises also stop of in Vidin for a day. The synagogue is located near Baba Vida Fortress, which is on the bank of the Danube River. There is a park along the Danube riverbank, and if you walk through it with the river on your right, you will eventually see the synagogue to your left, right before you reach Baba Vida. It is abandoned and thus open to whoever want to go inside. There is a fence around it and many overgrown plants, but the short part of the fence has a part that is completely cut away, and it is quite easy to find.
It is recommended that you only go inside during the day time and wear closed-toed shoes because is broken glass inside. The stairs to the second floor still seem to be structurally sound, so you can climb up there if you want. There will probably be young people hanging out inside the building, so don't be afraid if you hear people inside during the day.