Of Bath’s three naturally-heated thermal springs, the largest rises in the King’s Bath – part of the Roman Bath’s tour and the only place where you can see the waters bubbling up to the surface from a vast underground lake about two miles under the surface.

It’s also the place where you can look back through two thousand years of history and architecture from the Roman occupation to the present.

The King’s Bath was built above the ruins of the Roman bathing complex – all but forgotten beneath. Around it is 17th-century stonework but the floor was cut away – searching for the contaminating bug discovered in the water – and revealing the ‘sacred spring’ enclosure beneath.

As a Mayor’s Guide, l love leading my group through to the balcony looking down on the enclosure and explaining a little of what they can see and could imagine.

Unfortunately, the view is likely to be a bit restricted from now until November. Scaffolding has gone up on the walls around the King’s Bath and notices explain that it is so conservators can clean and conserve the stonework.

It’s a necessary inconvenience. Bath stone is a superb building material – and great to carve – but it does get dirty and affected by pollution. It mustn’t be allowed to erode or corrode.