Mapledurham House and Watermill is an impressive historic building. Wander through the restored interior and get a feel for what life was like for the former inhabitants.
You're spoiled for sightseeing choice when in Reading. Mapledurham House and Watermill is a good place to start here, but there are lots of other interesting spots to consider. University of Reading, Madejski Stadium, and Reading Abbey Ruins are not far from the historically significant residence and and will cap off your day nicely.