One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

The famous sculptor left his mark on this Italian wall in an internationally protected example of street art.

The Pope’s secret escape route.

An ossuary built in 1210 to collect bones from the Ospedale Maggiore of Milan.

Milan's duomo is covered in beautiful carving including a curious "dinosaur-like" beast.

Legends surround an ancient tree trunk riddled with nails for good luck.

A patriotic medieval knight in driven-nail armor raised money for widows and orphans of WWI.

Beautiful Austrian natural history museum with carved ceilings and row after row of ancient taxidermy.

Go inside to really appreciate this 500-year-old technological masterpiece.

The most visited, and possibly most controversial, museum in Germany.

The celebrated eyesore created by starry-eyed sweethearts.

This former “ante-chamber to the guillotine” has been refurbished to illustrate the brutal history of French justice.

France's most famous cemetery, with some of its most curious tombs.

Paris' linguistic guide to the international language of, yes, love.

The only "Egyptian" pyramid in Europe and the legendary tomb of Remus.

One of Catholicism's four major basilicas has a series of papal portraits that are said to predict the end of the world.

This former Roman Catholic Church still contains the embalmed hearts and organs of 22 popes.

An old department store turned Nazi prison turned artist commune.

Breathtaking and huge 430 year old maps of Italy.

Madrid's romantically ornate crystal palace has been offering shelter to plants and art for over a century.

This semi-secret storybook hedge maze is also the oldest garden in the city.

César Baldaccini's iconic sculpture of a 40-foot thumb stands tall in La Défense.

This ancient Greek place of assembly and marketplace is being revealed layer by layer below the modern Athens cityscape.

The incorrupt tongue of the patron saint of lost things is venerated in this basilica.