This private skyway is filled with art and was expanded explicitly so that Hitler could appreciate a river.

A treasure trove of Renaissance-era funerary art in a Roman church built on top of Nero's grave.

One of Catholicism's four major basilicas has a series of papal portraits that are said to predict the end of the world.

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

Jesus' footprints and the first catacombs in the world.

2300-year-old Roman road connecting the empire.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

Construction of Barcelona’s iconic (but controversial) church was finally completed in 2026—a century after the death of its architect.

A vista of the city and sea from atop the little-known viewing deck on an unassuming Columbus statue.

Granting the right of way to ships over surface traffic since 1917.

This working class sculpture pounds his hammer all the livelong day.

An abandoned network of military bunkers and tunnels open for anyone willing to descend into the darkness.

The tech giant built three enormous glass orbs in Seattle so employees could work inside a rainforest greenhouse.

Nuclear reactor created the plutonium used on Nagasaki.

This playground sculpture of an icon from the past is dedicated to the children of the future.

This metallic stampede sits frozen on a Washington ridge yet the artist's vision is still incomplete.

This famous bridge twisted itself into oblivion, but not for the reason you might think.

Site of the greatest known waterfall that ever existed.

One small town in the Pacific Northwest transformed itself into a Bavarian-themed tourist destination.

A whimsical village of unique treehouses resides in a Washington forest.

This former coal gasification plant found a curious second life as a popular public park.

A wall of chewing gum moonlights as collective art.

A museum dedicated to the history and exploration of both popular music and science fiction.