This unusual round church was situated just about 5 minutes walk away from our hotel, and is yet another remnant of the Baths of Diocletian complex, with a “twin” rotunda (minus the stucco) situated a few streets away at Via Viminale, and now incorporated into a restaurant!. Each is suspected to have been an entrance into the Baths and/or their library.
A Caterina Sforza (not the one featured in the Borgias but presumably a relation) paid for the conversion to a church in the late 1500s – by which time the whole area was well on its way to emerging from the decline suffered with the end of Empire.
Like the Pantheon, there’s even an oculus …