What was supposed to be a 6km-long dam during the communist era, left abandoned after the 1989 Revolution, turned over 22 years into a vast urban delta. The first of its kind in Romania, this nature park has 136 species of birds and 116 types of plants, reptiles and insects, an entire ecosystem thriving among concrete structures. Call ahead to visit the 17th-floor Observatory in Asmita Gardens’ T4 Tower (free entry).