The difficulties which present themselves in any attempt to describe the architecture still continue to beset us; such earlier drawings as we have are contradictory and rude to a degree.[38] The NAVE was Norman, rebuilt to a great extent after the fire of 1137. The aisles had the usual round-headed windows, with the unusual (for England) circular windows above. There were flat buttresses; but I must reject the flying-buttresses of some restorers. The clerestory windows are a puzzle. Everybody maintains they were Pointed, and, if so, they would have been inserted at the same time as the new roof; but there seems to be no trustworthy authority for this. In Finden's engravings after Hollar they are taken at a peculiar angle which is apt to mislead. Hollar and his engravers give two windows on the south side in the interior, _i.e._, of the nave and clerestory. Both seem alike; and Inigo Jones' patched-up north and south fronts represent them both as round, so that the balance of evidence appears to be in favour of round.[39] Another difficulty is the question of the existence or nonexistence of the western towers. Mr. William Longman and Mr. E.B. Ferrey give none in their south-west view, because "no drawings or plates are known to exist which would settle the question." But it is our misfortune that we have to reconstruct Old St. Paul's practically without the help of drawings, until we come to Inigo Jones' finished work. In Dugdale's ground-plan they cover almost exactly the same area as one of the severies of the neighbouring aisles, and are flush with the west front; in both respects resembling those of Wells and other cathedrals. Besides, they are constantly mentioned, and at various dates, as Mr. Longman duly acknowledges. The southern tower was the original LOLLARDS' TOWER from which the Lambeth tower has borrowed its name, and was utilised for a prison by the Bishops of London for ecclesiastical offences. It was both bell and clock tower, and abutted on to both the cathedral proper and St. Gregory's. So late as 1573, Peter Burchet of the Middle Temple, shortly afterwards executed for murdering his gaoler in the tower, was imprisoned here for heresy, and would then have been sentenced to death but for recanting.