Travelers exchange letters with woodland creatures at this mini post office.

Huge masonic hall in Philadelphia with lavishly themed rooms.

This sculpture by artist Fritz Keonig survived the 9/11 attacks and now stands as a monument to the victims.

A storybook European village in Berkeley.

A "Titanic" superfan changed his name to Jack and set up this strange shrine to the blockbuster, complete with Korean food and Tarot readings.

These aggressively sustainable art homes look like something out of 1970's science fiction.

Yale University's home for rare works, including the mysterious Voynich Manuscript.

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

Treehouse motel and treehouse-building school.

Nonprofit art center that promotes outsider, intuitive, and self-taught art.

By day this New Orleans square is for pedestrians, but by night it is a kingdom of kittens.

The largest drain hole in the world.

Sandstone rock formations that look like they belong on the cover of a progressive rock album.

Stay in a room with a view... of the bottom of the ocean.

A popular European tradition makes its way to the states on one of America's most famous bridges.

The former home of the Nobel Prize-winning American writer is now home to dozens of six-toed cats.

When ecosystems collide in the arid Southwest.

First a horse rendering plant, then a 19th century landfill, this beach is full of glass from thousands upon thousands of broken bottles.

The Boston square dedicated to the dark poet who was born nearby.

This small-town Connecticut restaurant gives each diner a free book from its vast library.

An abandoned village that doubled as "The Hunger Games"' post-apocalyptic wasteland is up for grabs.

The remains of the first punk club in L.A.

Leaf through over 30,000 artists' sketchbooks in what may be the world's largest collection of doodles

Mysterious ancient boulder carved with petroglyphs in the mountains of Western North Carolina.