This eye-popping Icelandic crater lake is surrounded by red volcanic rock.

One of the few remaining casualties of the London Blitz, this destroyed church has become an enchanting public garden.

The first geometric self-supporting spiral stairs in Britain are a truly beautiful sight.

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

Life-sized sculpture of a blue whale made of hand-recycled plastic trash.

Nature's biggest mammal swims in landlocked Oklahoma.

The only diamond mine in the world where you can keep what you find.

One of the oldest living oak trees in the Southeast.

This massive stained-glass masterpiece is thought to be the largest Tiffany dome in existence.

Ride aboard a centuries-year-old steam engine and explore dozens of trains parts, including an unusual "comboose."

A bizarre house filled with an astounding array of collections.

No one knows how this Pacific Northwest spruce tree came to have so many trunks.

This seaside Italian village doesn't just look Escher-esque, it actually inspired the mind-bending artist.

Recognized the world over as the home of the McCallisters in the 1990 movie "Home Alone."

One of the best-preserved Roman amphitheaters is still used today, but for less brutal events.

This modern labyrinth lies in the shadow of a ruined medieval castle.

This futuristically sylvan church is a glass-enclosed marvel of modern architecture.