CAHOKIA — The historic Jarrot Mansion will open its doors to visitors from noon to 4 p.m. Saturday.

Built in about 1810 by entrepreneur and land speculator Nicholas Jarrot, the home is the oldest masonry residence in Illinois. It is undergoing reconstruction and usually is closed to the public.

The open house is part of a festive day that will close with a musical program at 4:45 p.m. at the Holy Family Parish Log Church followed by a 5 p.m. Mass and a chicken and dumplings dinner in the parish hall. The dinner is free, but donations are encouraged.

Jarrot Mansion is located at 124 E. First St in Cahokia.

The Cahokia Courthouse, built about 1740, will be open from 9 a.m. to 4 p.m.