A monument to Poland's famous alleged UFO abduction case.

A tribute to the Polish insurgents who fought in the failed attempt to end their city's Nazi occupation.

A 20th-century picture show in 3-D.

Warsaw's fantastically preserved gasworks...almost.

A program of Communist glamour in post-Stalin Poland is preserved in this colorful museum.

After the famous composer died in Paris, his sister snuck his heart out of the country to honor his wish that it be buried in their native country.

Crosses of all shapes, sizes and colors litter the mountain, the site of a huge yearly Orthodox pilgrimage.

An underground city of salt.

Poland's oldest surviving university building holds a wealth of historic science instruments including some used by Copernicus.

Beneath Kraków Old Town's main square lies a hologram-filled medieval market vampire graveyard wonderland.

Wars fought and wars won are remembered by these abandoned bunker ruins.

Legend has it that not even Stalin could pull down the 2015 European Tree of the Year.

Mysterious craters may have been home to an ancient cult.

Two old windmills got a new life as oversized sculptures of a man and a woman.

The ruins of an Estonian prison are drowning in the quarry lake where the convicts were once forced to work.

The gutted remains of this Estonian mansion are a monument to a tragic love.

This disappearing geyser has been attributed to witchcraft, but really it's all about rainfall.

A cluttered and astounding collection of antiquities and curiosities.

The anatomical-pathological collection of a man who changed surgery.

Hear the quietest sound from across the dome.

Eighty million natural history specimens call this gargantuan museum home.

A community of artists and entrepreneurs seeks a simpler life on London's waterways.

This hidden rooftop garden in downtown London offers a quiet respite from a bustling city.

A 300-year-old tea shop that brought tea to the English people, not to mention the Queen herself.