Bucharest's most surprising green space: 183 hectares of reedbeds, ponds, and meadows on the southern edge of the centre, all of it occupying a half-finished Communist reservoir that nature reclaimed after 1989. Walking trails loop the basin, observation platforms look out over the water, and on a quiet morning you can watch egrets, kingfishers, and herons within sight of the city's tower blocks.
The reserve is run by volunteers and entry is free. Bring binoculars; the bird life is genuinely good and over 90 species have been counted. Easiest access is from the eastern entrance on Calea Văcărești, near the Sun Plaza shopping mall. Allow two or three hours for a proper walk around the perimeter.