River pirates, murderous bandits, and serial killers used this Illinois cave as their debauched hideout.

Now nearly abandoned, Kaskaskia was once the capital of Illinois and one of the most important towns on the upper Mississippi.

What was once a presidential estate is now an exotic menagerie and home to the Budweiser Clydesdales.

The Old Courthouse takes visitors on a captivating trip through St. Louis' timeline.

The lowest point in the state of Illinois, at the confluence of the Mississippi and Ohio rivers.

This monumental Jesus is often referred to as "Our Milk Carton With Arms."

Elvis's own personal tropical hideaway.

This Memphis recording studio launched the careers of Jerry Lee Lewis, Johnny Cash, and Elvis Presley.

The hotel where Martin Luther King Jr. was shot is now a museum dedicated to his work.

The somber sculptures commemorating Irish Famine on the river Liffey in Dublin.

A former fisherman's hut deemed too small for habitation is now a delightful tourist draw.

A wildlife paradise, this island is one of the world’s most important habitats for burrow nesting seabirds.

A proud bronze billy stands as an eternal symbol of Ireland's oldest festival, where a goat is made king.

This Welsh village gave itself a ridiculous name in a publicity stunt a century ahead of its time.

An abandoned quarrying village turned commune is now a hub for learning the Welsh language.

Mortarless walls that stretch for miles are a lovely solution for creating grazing land in the harsh terrain of the Aran Islands.

Impressive mining ruins overlook a spectacular view of Ireland's Copper Coast.

The ruins of an 800-year-old monastery boasts the tallest round tower in Ireland.

The comedy and tragedy of Oscar Wilde is preserved in a Dublin park, captured in a sculpture of colorful stone.

The gorgeous library at Trinity College is home to remarkable treasures of Irish identity.

If you can look past the nearby sewer pipes, this urban sinkhole grotto is a mini-paradise.

A flooded Mexican cave that hides a river beneath the water.

Every equinox this Maya pyramid puts on a spooky ancient light show.

Clap your hands at the base of the pyramid, and the song of a sacred Mayan bird will echo through the air.