This large, circular tomb is the final resting place of the first emperor of Rome.

An ancient Roman temple first dedicated to an emperor's wife is now a church.

The underground sanctuary of a mysterious ancient cult.

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

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

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

The spot where the fascist dictator made some of his most famous speeches including declaring war on Britain and France.

A detailed pachyderm supports Rome's smallest Egyptian obelisk.

Hundreds of lucky felines haunt the ruins where Caesar was murdered.

A swing to dangle you off the very edge.

A devastated ruin in the south of Belize where British explorers claimed to unearth the Mitchell-Hedges Crystal Skull.

The sister plane of the C-123 shot down during the Iran-Contra Affair has found a new purpose in retirement.

A sculpture made of 10 Cadillacs as a monument to the "Golden Age" of the American automobile.

This small interfaith chapel lies not far from the rim of the Grand Canyon.

Most-visited and most-photographed slot canyon in the American Southwest.

The hike through a narrow river flanked by the 2,000-foot-tall walls of Zion Canyon is one of the best in the world.

The unusual patterns in this rock formation result from two distinct modes of weathering.

A tunnel with windows, so you don't miss out on the impressive views.

This rugged area of red rocks and arches is often considered one of the most beautiful places on Earth.

Giant, natural amphitheaters made of delicate geological formations called "hoodoos."

A striking, menacing sandstone peak towering above a landscape that's equal parts Mordor and the Moon.

The fifth-longest natural arch in the world, and the longest outside China.

This raised bulls-eye visible from space was the subject of an intense geologic controversy.

Few things look more out of place than the electric blue ponds in the reddish-brown desert of Utah.