Old St Paul's Cathedral in length including the portico, and across the transepts, and Winchester Cathedral, the longest remaining medieval church, is long and across the transepts. The cathedral had one of Europe's tallest church spires, the height of which is traditionally given as , surpassing all but Lincoln Cathedral. The King's Surveyor, Christopher Wren (1632–1723), judged that an overestimate and gave . William Benham noted that the cathedral probably "resembled in general outline that of Salisbury, but it was a hundred feet longer, and the spire was sixty or eighty feet higher. The tower was open internally as far as the base of
St Saviour's Cathedral, Goulburn as required, with a mass brickwork backing making up the rest of the wall. This dry press brickwork was to be laid integrally with the stonework in garden bond. The spire is yet to be completed. The spire remains an unfinished work. The Cathedral building is made of sandstone from a quarry at Marulan, except for the pillars which are of Pyrmont sandstone. The roof is natural slate. The Cathedral is unmistakably a Blacket church, on a grand scale, with nave, aisles, transepts, chancel, porches and tower. It has large and elaborate stone traceried windows and an impressive interior with