The Roman Baths sit in the middle of Bath, next to the abbey. You buy a timed ticket and walk a one-way route: terrace, Great Bath, rooms, artefacts, exit through the shop. You do not swim. The hot pool you can enter is around the corner at Thermae Bath Spa, a different building and a different price.
A spring the city was built on
The hot spring was already used before Rome. The Romans lined it and put a temple to Sulis Minerva next to the bath. After the empire left, the vaults collapsed and silted. Georgian Bath rebuilt itself as a spa town on top of the same water.
What you walk through is a excavated basement with a Victorian terrace added so visitors could look down. The green of the Great Bath is algae in daylight, not a sacred colour.
Why the queue is long
It is the one place in a honey-stone city that has a single obvious indoor circuit. The photograph is the terrace columns over the steam. What it leaves out is how fast the route dumps you into the gift shop, and how good the abbey square is if you step outside instead of stacking another museum.
Do not treat Bath as only this. The Circus and the Royal Crescent are the walk after.
If you go
Book morning — Tiqets already holds those Roman Baths slots. Train from Paddington is two hours on a good day. The audio guide is fine; you do not need a human tour. If you want to get in the water, book Thermae separately and do not try to do both before lunch.
