Olecko (former German: Marggrabowa since 1560, colloquially also Oletzko , Treuburg since 1928, Lithuanian: Alėcka) is a town in Masuria, in the Warmian-Masurian Voivodeship of Poland, near Ełk and Suwałki. It is situated at the mouth of the Lega river into the Great Olecko Lake (Jezioro Oleckie Wielkie) on its south-western shore. Olecko is the seat of Olecko County.