Brementennacum is the closest Roman fortress to where I live.
The baths were built approximately 100 AD and were in use for 125 years, until AD 225 where it was abandoned. It was initially built to serve the legionaries and auxiliaries garrisoned at the fortress, but in its later use the civilians in Brementennacum (Currently Ribchester) were also allowed to use the baths. The baths were built outside of Brementennacums' walls due to the potential risk of fire from the baths furnace in the early days, since initially the fortress was built from wood, and it wasnt until later it was rebuilt in stone.
Archeological discoveries at the bath house uncovered that Brementennacum was part of a trade route between other parts of Britannia and even Gaul throughout the empire and the time it was active as a fortress.

In the photos Ive taken above, you can see:
Top-
A Flue (center) leading into the furnace room (front) , with the Caldarium (Back right) and the Tepidarium (Back left) behind it.
Bottom
-A view from the Tepidarium (front) With the sweating room (behind the stairs) and a second furnace room to the right of it.