The east end of the church, and its high altar, are also positioned above the area where some basilicas of the period had a pagan shrine room (also known as an aedes).

[1] The possible existence of the shrine room is supported by nineteenth-century excavations under Gracechurch Street, immediately adjacent to the church's eastern end.

These unearthed an adjoining room covered in yellow panels with a black border, 'with a tessellated floor, suggesting it may have had a higher status than normal, possibly acting as an antechamber for the aedes or shrine-room'.

[5][6] The London Roman basilica, with most of the forum to the south, is thought to have been largely demolished around 300 AD,[7] with building material being removed (possibly for other projects) and the land levelled and eventually covered with a thick layer of dark soil.

The Tower Hill building was big, and similar in size and lay-out to the 4th-century Cathedral of St Tecla in Milan, the largest church in the Roman Empire at the time.

[15] Nonetheless there is precedent for early Christian churches and cathedrals to be built over Roman imperial structures and also on hills and geographic high points.

[17] The "table" (tablet) seen by Stow was destroyed when the medieval church was burnt in the Great Fire of London,[18] but before this time a number of writers had recorded what it said.

The text of the original tablet as printed by John Weever in 1631 began: Be hit known to al men, that the yeerys of our Lord God an clxxix [AD 179].

Lucius the fyrst christen kyng of this lond, then callyd Brytayne, fowndyd the fyrst chyrch in London, that is to sey, the Chyrch of Sent Peter apon Cornhyl, and he fowndyd ther an Archbishoppys See, and made that Chirch the Metropolitant, and cheef Chirch of this kingdom...[19]A replacement, in the form of an inscribed brass plate, was set up after the Great Fire[18] and still hangs in the church vestry.

The text of the brass plate has been printed several times, for example by George Godwin in 1839,[20] and an engraving of it was included in Robert Wilkinson's Londina Illustrata (1819–25).

They were referred to as co-conspirators in the somewhat gruesome murder of a deacon of St Peter's, Amise, who had been stabbed to death by the vicar of St. Paul's, London.

[23] A list of vicars in the church records the first known appointment as one John de Cabanicig in 1263, with the patronage being claimed by Pope Urban IV for 'long voidance'.

[29] The eastern frontage to Gracechurch Street is a grand stone-faced composition, with five arched windows between Ionic pilasters above a high stylobate (column base).

The tower is of brick, its leaded cupola topped with a small spire, which is in turn surmounted by a weather vane in the shape of St Peter's key.

[34] It is now a satellite church in the parish of St Helen's Bishopsgate and is used for staff training, Bible studies and a youth club.