Conurbations 

The towns of Ruse (170 000 inhabitants) and Giurgiu (70 000 inhabitants) are situated along the Danube, which marks the border between Bulgaria and Romania. Both cities are connected by the Friendship Bridge, the only Bulgarian-Romanian bridge built in the early 1950s. For several years, especially since the entry of Bulgaria and Romania into the European Union in 2007, Giurgiu and Ruse have joined within the Euroregion Danubius and developed various cross-border activities on the recovery of cultural heritage, natural areas, revitalization of urban and rural areas, and implementation of sustainable projects in different sectors of society. The most emblematic is probably the realization in 2002 of a university border, the European Inter-University Center Bulgarian-Romanian (BRIE).