An investigation into a structure elliptical in shape and with posts showing some kind of structure has been interpreted as a possible amphitheatre in Musselburgh. The area of the structure is about 30m in diameter and would allow around 1000 people to spectate standing on raised earth ramparts or sitting in a seated structure. The presence of cavalry in Inveresk fort makes it likely that some sort of training ring could also be used for spectators and dual-use of structures was known elsewhere.
There are other examples of amphitheatres associated with military installations – the Kunzing fort and amphitheatre are very similar to the design here and in that case enough archaeological evidence has been found to be sure. The Kunzing wooden enclosure also had a seating area and post holes have been found that match here. Also in Kunzing an altar to Mithras was found next to the amphitheatre which is true in Musselburgh. In Newstead (Trimontium) the confirmed amphitheatre next to fort is 30m x 37m in size. The most similar structure in shape and size in Britain is at Lunt Roman fort.
The full report into the possible amphitheatre is referenced below
Tim Neighbour, C. Clarke, G. Thomas, A Semi-Elliptical, Timber-Framed Structure at Inveresk (The Most Northerly Amphitheatre in the Empire?), Britannia, Vol. 38 (2007), pp. 125-140