The amphitheatre attached to the legionary fortress at Chester was first discovered in 1929, with investigations continuing in the early 1930s by Newstead and Droop, but it fell to Hugh Thompson to carry out more extensive excavations in the 1960s; these led to the consolidation and laying out of the northern half of the monument for public display in 1970–2. These excavations, published in Archaeologia 105 (1976), 127–239, presented an interpretation which proposed two amphitheatres, the first apparently constructed entirely of timber and dated to the late 70s, the second incorporating all the surviving masonry elements, dated to c. a.d. 100. The evidence for the timber amphitheatre was based on the discovery of extensive traces of radial and outer and inner ring-beam timbers (Thompson's ‘grillage’) preserved beneath the cavea of the stone amphitheatre. These were seen as rare and important additions to our knowledge of Roman timber amphitheatres more widely across the Roman Empire. A puzzling aspect of the stone amphitheatre was its apparent incorporation of two concentric outer walls.

However, following an important evaluation by K. Matthews, excavations were carried out by the authors on the Chester amphitheatre over three seasons (2004–6) as a joint venture sponsored by Chester City Council and English Heritage. This work has completely overthrown Thompson's principal interpretations. Meticulous excavation and recording have established that the ‘grillage’ supported timber seating arrangements associated with the second phase (1b) of an otherwise stone amphitheatre, and did not belong to a stand-alone timber structure. Amphitheatre 1a has a terminus post quem of a.d. 71, making it probably contemporary with the initial construction of the legionary fortress, while Phase 1b is some 20 years later, with a terminus post quem of a.d. 92–4, perhaps to be associated with the arrival of Legion XX Valeria Victrix. The first amphitheatre was almost completely demolished and replaced with a larger stone structure (Amphitheatre 2), c. a.d. 200. This is effectively Thompson's stone amphitheatre but without the inner of the two concentric outer walls, which we can now see was the outer wall of Amphitheatre 1. The construction of the new amphitheatre, which very probably included stone steps for seating, may be linked to an early third-century re-commissioning of the fortress. It is, by a small margin, the largest in Britain, just ahead of Caerleon and London, and it went out of use in the late third century.

Besides providing a radical new interpretation of the development of the Chester amphitheatre and characterisation of each of its phases, the excavation also produced important finds assemblages which shed light on early life in the fortress more generally (Phase 5), and also on the use of the amphitheatre itself, particularly in Phase 1b (Phase 7). This derives from the deposits contained between the two outer walls which give an extremely rare insight into a variety of activities associated with the life of the monument. On the one hand, a high proportion of the bones of domestic fowl relative to pig and sheep/goat and a large quantity of oyster may shed light on the food eaten by spectators; on the other, lenses of a soft, yellow, glacio-fluvial sand illuminate the running of the amphitheatre. They are interpreted as relating to the importation of sand from quarries a few kilometres to the east and north-east of the fortress to surface and re-surface the arena floor.

The report is beautifully illustrated, very largely in colour throughout, with illuminating reconstructions of the amphitheatres, including of the seating arrangements of Amphitheatre 1b (e.g. figs 73, 146–7). Together with its detailed reports on the artefacts and environmental evidence, this report makes an invaluable contribution to the study of the amphitheatres, not just of Britain, but of the Roman Empire.