Anstey Castle is a 12th century earthwork motte and bailey fortress, possibly founded by Eustace, Count of Boulogne. Standing at the south end of a broad spur, the large flat-topped motte is encased by a wet ditch and to the east is a ditched L-shaped bailey and a barbican. In 1218, Nicholas Anstey was ordered to destroy the additions to the castle, which was owned by King Henry III in 1225 and last documented in 1377. Excavations on the motte in 1902, revealed the trapezoidal uncut flint foundations and plain roofing tiles of a building. The dense cover of trees, makes it best viewed in winter. 2 miles south-east at Cole Green is Brent Pelham and 4 miles north-west at Barkway is Periwinkle Hill.