The whole area of the castle is 2-1/2 acres, including the annexe known as the Cockpit. This was certainly enclosed during the Norman period, as it has a Norman gateway in its wall. As we do not know the name of the site of Richmond before the Conquest, and as the name of Richmond is not mentioned in Domesday Book, we cannot tell whether the value of the manor had risen or fallen. But no part of Yorkshire was more flourishing at the time of the Survey than this wapentake of Gilling, which belonged to Earl Alan; in no district, except in the immediate neighbourhood of York, are there so many places where the value has risen. Yet the greater part of it was let out to under-tenants. ROCHESTER, Kent (Fig. 28).--Under the heading of Aylsford, Kent, the Survey tells us that "the bishop of Rochester holds as much of this land as is worth 17s. 4d. _in exchange for the land in which the castle sits_."[610] Rochester was a Roman _castrum_, and portions of its Roman wall have recently been found.[611] The fact that various old charters speak of the _castellum_ of Rochester has led some authorities to believe that there was a castle there in Saxon times, but the context of these charters shows plainly that the words _castellum Roffense_ were equivalent to _Castrum Roffense_ or _Hrofesceastre_.[612] Otherwise there is not a particle of evidence for the existence of a castle at Rochester in pre-Norman times, and the passage in Domesday quoted above shows that William's castle was a new erection, built on land obtained by exchange from the church.