Castle Hrastovec, located on the hill above the valley of the river Pesnica, is one of the mightiest castles of Slovenian Styria. The name Hrastovec (originally Gvtenhage) is first mentioned in the Styrian state urbarium for the year 1265. It is assumed, however, that the first mentioning of Gvtenhage does not refer to Hrastovec castle as we now know it, but probably to a small settlement or a much smaller stronghold on the hill. The existence of a smaller castle or stronghold in Hrastovec is proven in 1294.

The Herberstein family were the most powerful and prominent owners of Hrastovec castle. The famous diplomat and intellectual Sigismund (Žiga) Herberstein (1486-1566) was a renowned member of the family and visited Hrastovec castle on several occasions. The family greatly expanded the castle and the whole estate, of which they remained the owners until 1802, when it was bought by the Pauer brothers. In 1909 the Herberteins bought the castle back and it remained in their possession until the Second World War. After the war, in 1948, the Hrastovec-Trate institution for the mentally disabled was founded in the castle. The organization still calls the castle complex its home. The stunning ponds below are also a part of the castle complex.