Outside the line of the Roman wall, to the south of the city, and west of the south gate, there is a district called Boley or Bullie Hill, which at one time was included in the fortifications of the present castle. It is a continuation of the ridge on which that castle stands, and has been separated from it by a ditch. This ditch once entirely surrounded it, and though it was partly filled up in the 18th century its line can still be traced. The area enclosed by this ditch was about 3 acres; the form appears to have been oblong. In the grounds of Satis House, one of the villas which have been built on this site, there still remains a conical artificial mound, much reduced in size, as it has been converted into a pleasure-ground with winding walks, but the retaining walls of these walks are composed of old materials; and towards the riverside there are still vestiges of an ancient wall.[613] We venture to think that this Boley Hill and its motte formed the original site of the (probably) wooden castle of William the Conqueror. Its nature, position, and size correspond to what we have already observed as characteristic of the first castles of the Conquest. It stands on land which originally belonged to the church of St Andrew, as Domesday Book tells us William's castle did.[614] The very name may be interpreted in favour of this theory.[615] And that there was no Roman or Saxon fortification on the spot is proved by excavations, which have shown that both a Roman and a Saxon cemetery occupied portions of the area.[616]