Ruse

Ruse is a city in Bulgaria on the bank of Danube. On the east side, there's a bridge, which is the border point with Romania, the Ruse-Giurgiu border crossing.

The Ruse-Giurgiu border crossing connects Bulgaria (Ruse) and Romania (Giurgiu). The border is the Danube River, which is traversed by the Friendship Bridge. Walking across the bridge is permitted. I've been told by people from Ruse that walking on the bridge is NOT permitted. Both Romanian and Bulgarian passport control is done in a single office on the Bulgarian end of the bridge.