A defensive brick building in Jarocin, defined in a 1496 document as a fortalitium, had presumably already been erected by the beginning of the 15th century. This building was then rebuilt, extended and eventually demolished. The building known locally as skarbczyk (the jewel box) is all that remains of it today. A lot of decorative fragments of Gothic furnace tiles, attesting a once opulent castle interior, have been uncovered here during the course of excavation work.
There is a two-storey brick and plaster building laid out on a rectangular plan and surrounded by what used to be moats by the pond in the southern part of the park. The domed turret adjoining the body of the building from the west was added a good while later. The main body has a tiled pitched roof. The walls are supported by strong corner abutments and framed rectangular window openings. A stone bas-relief of the Leszczyc coat of arms of the Radoliński family hangs above the portal on the tower elevation. The vaulted rooms inside have been preserved.
It is now the Jarocin branch of the Regional Museum.
References:The Broch of Gurness is an Iron Age broch village. Settlement here began sometime between 500 and 200 BC. At the centre of the settlement is a stone tower or broch, which once probably reached a height of around 10 metres. Its interior is divided into sections by upright slabs. The tower features two skins of drystone walls, with stone-floored galleries in between. These are accessed by steps. Stone ledges suggest that there was once an upper storey with a timber floor. The roof would have been thatched, surrounded by a wall walk linked by stairs to the ground floor. The broch features two hearths and a subterranean stone cistern with steps leading down into it. It is thought to have some religious significance, relating to an Iron Age cult of the underground.
The remains of the central tower are up to 3.6 metres high, and the stone walls are up to 4.1 metres thick.