The whole circuit of the wall is 2 miles and 605 feet. It is provided with battlements on the outside and a ledge or standing-place within, two or three feet wide, for the defenders. There may have been also some kind of rail for protection on the inside; the railing, however, sometimes found on old walls still existing, as at Chester, is modern; and we observe that the walls of York, Aigues Mortes, Avignon, and other places, are without any railing. Outside the wall lies the ditch, broad and deep, first constructed in the early part of the thirteenth century; the water is kept flowing by means of a culvert in the wall which leads it into the old bed of the Walbrook; it is renewed and kept fresh by certain small streams which fall into it from the Moorfields; it is full of fish, but since nothing can keep the people from throwing things into it, the water is always growing more shallow and the ditch always needs more dredging. The White Tower is built upon the original eastern end of the wall. Just north of the Tower on the east side is a postern of late date giving access to the riverside; and it serves as access to two religious houses, but there are no dwelling-houses there. St. Katherine’s by the Tower, one of the religious houses, stands on the bank of the river. It is quite a small foundation, but from the beginning it has been closely connected with the Queens of England. On the north of St. Katherine’s rises the stately Abbey of Grace, Graces, or Eastminster, not one of the most wealthy monasteries, but an important house, provided with very beautiful buildings (see vol. ii. pt. iii. ch. xxvi.). Between the ditch and the monastery is the open space called Little Tower Hill with its Stone Cross. [Illustration: ST. KATHERINE’S BY THE TOWER From Dugdale’s _Monasticon_.] The Town Ditch begins just south of Smithfield at the angle. There is no ditch along the west wall; probably there never was any, the Fleet River serving here for the moat. There is a Bridge over the ditch for the Grey Friars’ Postern, and another outside Aldersgate.