Castle Garth is a road in the centre of Newcastle, notable for the 12th century Keep of Newcastle Castle, Moot Hall, The Bridge Hotel, and the Old County Hall for Northumberland. Garth typically meant an enclosed space: there were once outer castle walls around the Keep. Most of the outer defences of the castle were demolished, but the Black Tower and South Postern tower remain. Castle Stairs and Dog Leap Stairs lead from Castle Garth down to Sandhill and Side, respectively, by the Quayside area. The medieval castle was itself built on the site of the Roman Fort 'Pons Aelius'; a small section of the remains of Pons Aelius can be seen under a railway arch at the north of Castle Garth.