The world’s largest truck stop includes a barber shop, chiropractor, and a huge museum with antique trucks.

In rural Iowa, an imported 19th-century windmill overlooks an unlikely enclave of Danish culture.

At a mile long, the Fort Madison Bridge is the largest double-decker swing-span bridge in the world.

An underground wonderland in Iowa.

How did the 110-foot limestone statue cross the road?

Chilly air billows out from the entrance of an abandoned mine on a steep hillside, providing a refuge for Ice Age fauna and flora.

A pop-culture attraction outside of Dyersville, Iowa, hits a home run.

A half-mile long and three stories high, this bridge over the Des Moines River Valley mimics a descent into a mine shaft.

A warning to the weak-kneed: This narrow bridge does its swinging eight stories high.

Since World War II people have been decorating this stretch of the Yuma desert with signatures arranged out of rocks.

Huge hole looks down onto an underground beach populated with sea lions.

The "world's smallest volcano" has been used to store meals and dispose of dead bodies.

Take a dip beneath the stalactites in this amazing cenote.

A lake at the bottom of the ocean.

This ancient structure was built by a mysterious civilization that was largely destroyed by a volcanic eruption.

This popular cave pool is truly magical, despite the crowds.

This "cursed house" features secret rooms, hidden vaults, and dark escape tunnels.

These enigmatic columns tower over the ruins of an ancient Toltec city.

Three sinkholes filled with warm, crystal-clear water reached by a horse-driven cart on an old train track through the jungle.

The ruins of an ancient city built by Mayan traders is centered around a temple of a sacred feathered serpent deity.

The enigmatic and seldom visited ruins of a Mayan city-state.

Beach instrument turned bed and breakfast.

The stoutest tree in the world.

The hot chocolate here all stems from small, sustainable microproducers in Chiapas and Tabasco.