Bailey Hill is a late 11th century earthwork motte and baileys fortress, founded by Robert de Montalt. A hillock was scarped to create a steep-sided motte, with two southern rectilinear baileys laying in-line as they drop down the slope, of this naturally strong site. In 1147, the castle was taken by Owain Gwynedd and in 1167 minor royal expenditure is recorded, after the area was recovered by King Henry II. Traces of masonry, have been noted on the summit of the motte and two stone walls of a possible hall have been located in the inner bailey. The castle was last mentioned in 1244 but since 1792 the site as been used as a recreation garden. The construction of a bowling green, which now occupies the inner bailey and the Gorstedd Stone Circle on the northern side of the motte, have also affected the site. 2 miles south-east is Tyddyn Mount Mold and 6 miles south-east is Caergwrle Castle.