This singular Irish dolmen is more Frank Lloyd Wright than upright stonehenge.

The oldest public library in Ireland.

An 1814 castle that hosts an exhibit of "explorabilia".

This beautifully designed star-shaped fort was the premier defense system of the late 1500s.

This community on a small Venetian island has taken to painting their houses in bright neon hues.

The topiary maze at the Habsburg hunting lodge.

A centuries old castle atop a dormant volcano houses museums devoted to both women and witches.

Originally envisioned by King Ludwig II to rival Versailles, Herrenchiemsee's "New Palace" remains half-gilded for lack of funds.

A striking 12th-century-style castle built on the edge of a cliff.

A unique form of erosion created an uncanny landscape of boulders perched atop slender columns of clay.

This Luxembourg cave is covered in cryptic looking marks left by mining activity.

This tri-part waterfall is a little bit of fairytale beauty in the heart of Luxembourg's Little Switzerland.

The world's first zoo for microbes collecting the horrible and wonderful things living on and around us.

Denmark's famous pseudo-hill.

An icy lake tucked among jaw-dropping alpine panoramas.

A magnificent, iconic stone tower in the Scottish Highlands.

Granite rocks that concentrate waves into powerful jets.

The world's largest reflecting pool is just two centimeters deep.

65 million-year-old chalk outcroppings mark the end of the Jurassic Coast.

Swiss vineyards in a UNESCO heritage site.

The world's northernmost ice hotel.

Certain traditions prevail on the least-visited island of the Aran Islands.

A lake at the bottom of the ocean.

This Scottish manor house is a lush relic from the life of a literary great.