| Shizvestus |
There are Gladitorial arenas in Kaer Maga, and Riddle Port (run by Monks) in Varisia. In Cheliax there is a Monk Run Gladiatorial arena in the Old Capitol. There is one run by Monks I believe in the City at the Center of the World. There is a Fighting Monastery somewhere in the mountains
in Taldor and they would have a tournament training arena. They are all over.
| Ayronis |
Tymon, in the River Kingdoms, is what you are looking for. It is covered in the story portion of Pathfinder #35.
"Pathfinder Ollix Kaddar’s adventures in the gladiator pits of Tymon in the Pathfinder's Journal, by Steven E. Schend."
There are a few references to Taldor having a gladiatorial tradition as well.
| Patrick Renie |
I think there was one also in the southern area of the Sodden Lands.
Yep, you're thinking of Green Blood on a Black Rock, a gladiatorial event located in the town of Greenblood near the southern edge of the Sodden Lands. Gamblers from all over the region go to Greenblood to watch and bet on brutal fights between slave-monsters such as scrags, trolls, and even more ferocious beasts. The battles take place on a lonely, ash-colored rock just off the shore, and whichever captured monster wins the fight earns its freedom.
More on Greenblood can be found in the Inner Sea World Guide.