Trostianets (also Trostyanets; Ukrainian: Тростянець) is a city in Sumy Oblast of Ukraine, the center of Trostianetskyi Raion. It's located on Boromlya River, 59 km (37 mi) from Sumy. The city population is 23,300 (2001). The district of Trostyanets has 49 settlements, inhabited by 41,700 people governed by 16 village councils and the town.
Local sights include the neo-Gothic "round courtyard" (1749), the late Baroque church of the Annunciation (1744–50), 18th-century Galitzine palace, and a "grotto of nymphs", built in 1809 to mark the centenary of the Battle of Poltava.