Elagabalium (temple) built
221 CE.
Shown on the map at 41.890°, 12.489°.
The Elagabalium was a temple built by the Roman emperor Elagabalus, located on the north-east corner of the Palatine Hill. During Elagabalus' reign from 218 until 222, the Elagabalium was the center of a controversial religious cult, dedicated to Elagabalus, of which the emperor himself was the high priest.
Text from the Wikipedia article Elagabalium, licensed CC BY-SA 4.0.