Halton Castle in Runcorn was built around 1070 as a Norman fortress controlling an important crossing over the Mersey estuary, originally constructed in timber before the de Lacy family rebuilt it as a substantial stone fortification. Serving as the seat of the Barons of Halton from the 11th century through the 14th century, it later passed to the Duchy of Lancaster. During the English Civil War, Parliamentarian forces under Sir William Brereton besieged the Royalist-held castle twice in 1643 and 1644; a 1646 Council of War decision dismantled its fortifications, ending its military role. Today, visitors can see the remains of the curtain wall, several ruined towers, an 18th-century courthouse now operating as a public house, and a Victorian folly. Designated as a Grade I listed building and scheduled ancient monument, it continues to represent medieval military heritage.