Within the gate at the east end of this range of buildings is the guard-house, behind which is a venerable tower, called _Julius Agricola’s_, or _Cæsar’s_, which is still entire, and partly occupied as a magazine. Within this tower is a curious chapel, mentioned in the tax-book of Henry VIII. as the chantry “_infra Castrum Cestriæ_” and yielding as its tenth 10s. 8d. It is an upper chamber, about 19 feet by 16, and 16 feet in height. The roof, which is vaulted and groined, is of stone. On one side is a plain pointed recess in the wall, the back of which appears to have been ornamented with paintings, and was probably the altar. James II. heard mass in this chapel. THE GAOL AND COUNTY HALL. The principal entrance to the Shire Hall is through a portico of twelve columns in double rows, 22 feet high, and 3 feet 1½ inches in diameter, each formed of a single stone. The ceiling, roof, and covering, are also of stone. The hall is of a semicircular form, measuring 80 feet by 50, including the judgment-seat, and 44 feet high, and is lighted from above. The ceiling is a semi-dome, boldly caissoned with ventilators opening to the roof, in the shape of ornamental roses. It is supported by a row of twelve Ionic columns, each composed of a single stone, from the bases of which there is a gradual descent by a flight of circular steps to the bar, which enables every one in the body of the court to have a perfect view of the judges, counsel, prisoners, and witnesses. There is a subterraneous passage from the dock to the prison, which affords both facility and safety in the removal of the prisoners. On the right of the entrance to the County Hall are the Grand Jury Room and the Prothonotary’s Offices. In a small room on the ground floor is the model of the Grosvenor Bridge, and there are full length portraits of William III., Charles II., George I., George II., and Frederick, Prince of Wales.