The protected area of the former Onuškis Manor, together with its park, covers 15.5 ha. Onuškis Manor is mentioned as early as 1522. In the 18th century the Onuškis estate belonged to the Rajecki family. At the turn of the 18th and 19th centuries Onuškis was bought by Józef Komar (owner of Raguvėlė Manor), who died in 1849. His son Teofil (1800–1861) built a late Classicist palace at Onuškis, whose façade boasted 11 columns facing the park. The palace is believed to have been designed by Cezary Anichini, a famous architect of the time. After the death of the palace's builder, T. Komar, the manor was run by his son Władysław Komar (1848–1896), and after his death by his wife Maria and their children. Through marriage the manor passed to the Krasicki family, and in 1922, when the land reform began, it was parcelled out. The Onuškis palace burned down during the First World War, yet its picturesque ruins survived even the Second World War and still stand today. There are now two ponds in the park. More than 21 species of native trees and shrubs grow here. Impressive European larches and a Weymouth pine that splits into two trunks stand out. There are also silver birches, oaks, ashes and stout maples. A spruce grove grows in the north-western part of the park. Onuškis Manor and its park are neglected and in poor condition.