Santa Maria Antiqua (Roman Forum)

The oldest and most important Byzantine church in the Western world — a 5th-century church built directly into the Palatine Hill's ramp structure inside the Roman Forum, containing layer upon layer of extraordinary frescoes from the 6th to the 9th centuries. Abandoned after an earthquake in 847 AD buried it under rubble, the church was literally sealed and preserved for a millennium, which is why its frescoes — covering every wall, arch, and vault — survive in extraordinary condition. The earliest layers, from around 550 AD, show Greek-Byzantine figures of pure golden refinement. Later papal commissions (Pope John VII, Pope Zacharias) added more. The rarest single collection of early Christian painting in any building in the world. Accessible via the SUPER Pass for the Colosseum/Forum, or with a dedicated ticket on days it is open.