Zagarolo is built on top of a hill in Latium (Lazio in Italian). As
you can see from the pictures, adding plumbing to the ancient town was a
challenge - bathrooms are added on to the houses and the plumbing tends
to be improvised.
Mostly renaissance, with fragments of Roman columns or artifacts
incorporated in buildings, Zagarolo does not even appear on any of the
many guides I checked.
Like most small towns around Rome, it's packed with art treasures -
it's a well kept secret, only known to the locals.