With over 100 jam-packed rooms to explore plus elaborate tea services and events, the Mansion on O Street is a hidden treasure.

Long-abandoned trolley tunnels just a mile away from the White House are turning into an art space.

A wondrous old library overlooking the nation's capital.

A lovely aquatic park built by a one-armed Civil War veteran who made a fortune from lotuses.

A rotating cast of guys and dolls in front of a Washington, D.C. building.

This Bronze Age tomb is the centerpiece of a clearing within a beautiful Irish forest.

A nun spent 16 years painting the stunning Celtic mural that covers the interior of this WWI memorial.

The oldest public library in Ireland.

The enchanting archway is the only surviving portal into Dublin's lost medieval wall.

Some of the saint's blood and bones are said to reside in Dublin.

The mummified heart of a saint lives on in this church—after a brief hiatus when it was stolen.

The fountain marks the area where hundreds of accused witches were burned at the stake.

This indie movie theater is one of only three surviving Mayan-themed theaters designed by “Detroit’s greatest theater architect.”