Olivers Battery is a large 11th century earthwork motte and baileys fortress, founded by Hugh de Port. Standing on the north-west corner, is a low motte but this half of the enclosure, is been badly damaged by ploughing. A cross-bank divides the two baileys and a low rampart, with a wet ditch, encases the eastern half of the castle. At the south-west corner, is the present and what would appear to be the original entrance. The predecessor to Basing House, siege guns were set up in the castle, in July 1644, giving the site its Civil war name. 6 miles east is Odiham Castle.