The old Roman Agora, or marketplace, was built some time around 100 BC, I believe. The Romans took over Thessaloniki around 168 BC, so it was built some time shortly thereafter. It seems logical to assume that the Apostle Paul would have been here during his stays in the city. I think you can walk through parts of the site, but again it was closed when we went. (This is probably going to be a reoccuring theme around here. Schedules, maps and the like are rare, and the ones that do exist are constantly changing.) Above is a photo of what we think was a pool located in one corner of the agora.