This curious, round temple is the oldest still-standing marble building in Rome.

A large replica of a monumental Roman inscription is located on the side of this museum.

The remains of this 2nd-century Roman temple are incorporated into a modern building.

This former Roman Catholic Church still contains the embalmed hearts and organs of 22 popes.

This small, ancient Roman temple was once a church dedicated to the patron saint of penitents.

The only remaining arch of the oldest stone bridge in Rome stands in the middle of the Tiber.

The yawning maw of this pagan visage is said to bite off the hands of liars.

In the early Roman Empire, people deemed traitors and criminals were tossed to their deaths from this rock.

This small church was constructed over the ruins of three temples dating to the Roman Republic.

This ancient market is often referred to as the oldest shopping mall in the world.

The largest hot spring in the United States is, as the name suggests, a stunning show of natural color.

Jesus' footprints and the first catacombs in the world.

One of several skulls claiming to belong to the beheaded St. John the Baptist is on display at this Roman church.

The ruins of the largest gladiatorial school in Rome are largely hidden under modern streets.

2300-year-old Roman road connecting the empire.

This Roman arch marks the location of an ancient gate at one of the Seven Hills of Rome.

A sculpture serving as an homage to Pope John Paul II.

More sculpture than building, this architecturally significant temple was built on the spot of Saint Peter's crucifixion.

This one-of-a-kind Roman arch is not actually dedicated to the god Janus.

This ritzy Italian market is built around a statue of an unforgiven heretic who was burned for his belief in an endless universe.

An amazing collection of fantastic reptiles, amphibians, spiders, and insects.

Strange red rock formations that have been attributed to a higher power for hundreds of years.

This erect, phallic geological spire wasn't always named so domestically.

The Denver airport is guarded by a 32-foot-tall sculpture of a demonic horse.