The old observatory in Copenhagen has a spiral corridor used as a racetrack.

Copenhagen's celebrated theme park and gardens.

A toweringly silly piece of modern art has been delighting locals since the 1980s.

The oldest remaining frame residence in Minneapolis.

The only arched bridge made of stone on the entire Mississippi River.

When flour explodes, it's not a pretty sight.

This iconic water tower and failed bandstand is open for panoramic views once a year.

This taxidermic smorgasbord was co-created by an artist poached from the Museum of Natural History.

20,000 pieces in a Frank Gehry-designed building.

The highest point in Wisconsin is capped by two towers that are not as mythic as Tolkien's but provide much better views.

These Great Lakes sea caves accessible by boat in the summer turn into temples of ice reachable by foot in the winter.

A restaurant and lodge in northern Wisconsin which served as a clandestine hideout for John Dillinger and featured one of the most famous botched FBI raids in history.

This picturesque cliffside beacon no longer calls to sailors but shines once a year in honor of a famous shipwreck.

One of Frank Lloyd Wright's final works was this UFO church.

A large circus museum with summer performances.

The Giant Lemon of Lemon Grove.

Not truly a ship nor a building, the Navy's first and last "landship" is now abandoned due to clerical issues.

An extraordinarily ornate museum in San Diego holds wondrous anthropological treasures.

North America's largest accredited model railroad museum.

Swarms of butterflies cannot compare to the awe inspired by the publicly-funded nakedness once displayed in this sunken garden.

The National Railway Museum in York is the largest railway museum in the world, attracting almost 1 million visitors per year.