It is likely enough that a great city like London would have had a citadel, and Tower Hill, situated at the angle of the wall by the river, seems itself to proclaim that from Roman days it has been a site of military importance. It has been doubted whether Roman buildings actually occupied the site, but some excavations in 1898-99 laid bare some remnants about three yards away from the south-west angle of the keep, together with a portion of a hypocaust.[109] Again, in the British Museum there is an ingot of silver found in the eighteenth century on the site of the Tower, and inscribed EX OFFI HONORII. A similar inscribed ingot was found not long since in the _castrum_ at Richborough, and this goes to raise the old theory of a treasury at the Tower again. The account given by William of Poitiers seems to show that the Conqueror took over and added to an existing stronghold (see Freeman), and Geoffrey of Monmouth, writing within the lifetime of those who were living at the Conquest, and when the Norman Tower was barely finished, attributes the "prodigiously big tower" by Billingsgate to Belinus. Elidure, a descendant of Belinus, he tells us, was shut up in the Tower at Trinovantum (London). All tradition is in favour of its having been a stronghold before the Conquest, and Henry of Huntingdon, _c._ 1130, says that Eadric's head after his execution by Cnut was placed on the highest battlement of the Tower of London. Again, there is no tradition of the Conqueror having taken land from the city for the foundation of his Tower. "Who built the Tower of London?" asks Dr. Maitland. "Let us read what the chronicler says of the year 1097: 'Also many shires which belonged to London for work were sorely harassed by the wall that they wrought around the Tower, and by the bridge, which had been nearly washed away, and by the work of the King's Hall that was wrought at Westminster.' There were shires or districts which from of old owed work of this kind to Londonbury."[110] According to the Welsh story, Bran the Blessed, King of Britain, "exalted from the crown of London," when wounded in battle commanded that his followers should cut off his head. "'And take you my head,' said he, 'unto the White Mount in London and bury it there with the face towards France.' And they buried the head in the White Mount. It was the third ill-fated disclosure when it was disinterred, as no invasion from across the sea came to this island while the head was in concealment." The White Hill is always explained to mean the Tower of London.[111]