Tempio di Minerva Medica

A domed monumental hall on via Giovanni Giolitti, wedged between the railway approaches to Termini and the blocks built for the new rione at the end of the nineteenth century, and visible from trains. Despite the name it is not a temple: it stood inside the precinct of a luxurious suburban residence, whose horti are argued as either the Horti Liciniani or the Horti Pallantiani. it.wikipedia dates it to the beginning of the fourth century and gives it as 24 metres high today and 32 metres originally, 25 metres wide, and about 470 square metres.