Monument to a suicide protesting the Soviet invasion.

The crypts of Capuchin friars decorated with the bones of over 4,000 friars, including an entire "crypt of pelvises."

The former private quarters and office of Dr. Sigmund Freud now hosts a museum housing the works of the founding father of psychoanalysis.

Op-art architecture designed for happiness.

Baroque celebration of the end of the Great Plague of Vienna.

The Habsburgs' royal collections of art and wonders.

The curious underground history of keeping Paris clean.

This bridge was constructed from the rubble of the infamous Bastille.

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.

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

Venice's island of the dead.

2300-year-old Roman road connecting the empire.

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

On the Spree bank, discover one of the last reminders of a symbolic wall that divided, and was torn down by the people.

Cold war icon and onetime "hole" in the iron curtain.

A museum dedicated to the history of a terrifying secret police is now held in their former headquarters.

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

Scattered throughout London are ancient remnants of the city's former bounding wall.

Hear the quietest sound from across the dome.

In this cobwebbed old operating theater, you can practically hear the screams of the unanesthetized patients.

This one has sailed five times as far as Sir Francis Drake's famous ship.

Tour the dark and beloved poet's former cobwebbed basement, which may have inspired "The Black Cat."

Huge masonic hall in Philadelphia with lavishly themed rooms.