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