We wrote about our visit to Poitiers (here, here, and here) after my opthalmic adventure, but didn't mention the ampitheatre.
For location, google maps (and the street names) hold the key.
What is brilliant is how the roman remains have been incorporated and woven into the fabric of everyday life. What is less brilliant is how much more survived until relatively recently: parts of the structure were demolished in the 17th, 18th and 19th century. Although to be fair the Wisigoths (love it!) also had something to do with it a bit earlier
We are always pleasantly surprise by Poitiers, but we actually visit very rarely - there is a 3 year gap between photos. When we first bought the house it's somewhere we thought we would be visiting often, but real life has turned out different.