York city walls

York has, since Roman times, been defended by walls of one form or another. To this day, substantial portions of the walls remain, and York has more miles of intact wall than any other city in England. They are known variously as York City Walls, the Bar Walls and the Roman walls (though this last is a misnomer as very little of the extant stonework is of Roman origin, and the course of the wall has been substantially altered since Roman times).

The original walls were built around 71 AD, when the Romans erected a fort (castra) occupying about 50 acres or 21.5 hectares near the banks of the River Ouse. The rectangle of walls was built as part of the fort's defences. The foundations and the line of about half of these Roman walls form part of the existing walls, as follows:

The line of the rest of the Roman wall went south-west from the east corner, crossing the via principalis of the fortress where King's Square is now located. The south corner was in what is now Feasegate, and from here the wall continued northwest to the west corner. The point where the wall crossed the via praetoria is marked by a plaque in St Helen's Square near the Mansion House.

The Multangular Tower in the Museum Gardens is the most noticeable and intact structure remaining from the Roman walls. It was constructed as part of a series of eight similar defensive towers. The walls are almost certainly the creation of Septimius Severus; however, the Multangular Tower is probably a later addition of Constantine the Great around 310–320 AD. It has ten sides, based on a regular fourteen-sided figure designed so that a circle through the internal angles of the internal face is tangential to the curve. The rear four sides are missing to provide access to the interior of the tower.

A low plinth or skirt extends out from the lowest course. It stands almost 30 feet (9.1 m) tall, has an external diameter of 48.5 feet (14.8 m) at the base and 46 feet (14 m) above the skirt. Length of each side varies from 7.5 feet (2.3 m) to 11 feet (3.4 m) on the inner face. The tower projects beyond the curtain wall to a distance of 36.75 feet (11.20 m). The foundations are concrete, atop which the tower extends having a rubble and mortar core between ashlar faced courses of small magnesian limestone blocks. At 15 feet (4.6 m) a scarcement reduces the thickness of the wall from 5 feet (1.5 m) to 3.25 feet (0.99 m), which continues for a further 4 feet (1.2 m) before being capped by 11 feet (3.4 m) of 13th century masonry in which arrowslits can be seen.

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