During the Roman period, the Guildhall was the site of an amphitheatre, the largest in Britannia, partial remains of which are on public display in the basement of Guildhall Art Gallery and the outline of whose arena is marked with a black circle on the paving of the courtyard in front of the hall. Indeed, the siting of the Saxon Guildhall here was probably due to the amphitheatre's remains. Excavations by Museum of London Archaeology at the entrance to Guildhall Yard exposed remains of the great 13th-century gatehouse built directly over the southern entrance to the Roman amphitheatre, which raises the possibility that enough of the Roman structure survived to influence the siting not only of the gatehouse and Guildhall itself but also of the church of St Lawrence Jewry whose strange alignment may shadow the elliptical form of the amphitheatre beneath.