Sostro (pronounced [ˈsoːstɾɔ]; German: Sostru[1]: 84, 108 ) is a formerly independent settlement in the eastern part of the capital Ljubljana in central Slovenia.

*Coster is presumably derived from Middle High German ze Ôster 'at the east', likely referring to the nearby castle at Osterberg (literally, 'east mountain'; Slovene: Ostri vrh)[1]: 107  above Podgrad.

[1]: 84, 108  For similar Slovene geographical names based on foreign-language prepositional phrases of location, compare Cmurek, Crngrob, Cven, Dragonja, and Spuhlja.

During the Second World War, Italian forces executed hostages below Dimnik Hill (Slovene: Dimnikov hrib) behind the village.

[7] A church dedicated to Saint Leonard (Slovene: sveti Lenart) was mentioned in written sources as early as the 14th century.