This Roman Amphitheatre is a remarkably complete set of high oval banks, hidden away in the depths of Cirencester. The original layout is still very clear and you can walk / climb all over the main bowl and the smaller ones around it (dogs and children permitted).
There is more information about the Amphitheatre at this web site.
Trees have now grown up on most sides around the site and the area is popular with local children and dog walkers. Although the cache is well concealed, it may be difficult to access at busy times. The cache is a large Ammo Box which started with many children-orientated swaps. When you replace the cache please ensure that it is hidden from view in every direction.
Whilst you are at the site you may be interested in the stone monument in the corner of the site, next to the road (on the left on your way out). It is now very overgrown and to get to it you’ll need to cross a small stream. At the time of hiding the cache, there was no way of safely crossing the stream but if you find out more about it then please post it here.
Whilst visiting Cirencester you may be interested in the Roman museum which is one of the best Roman museums anywhere. The museum is in the centre of Cirencester.
Parking is in the street next to the entrance at N51° 42.605' and W01° 58.294'.
An Ordnance Survey map for the location is available at this web site.
If you need the hint then the difficulty reduces to 1.
Please check out the Geocaching Association of Great Britain offering support for Geocachers in GB.