Once known throughout Europe, this tiny and unusually progressive 18th century micro-nation within Lithuania now lies in ruins.

No one knows who built this strange cave of worship or exactly why.

A centuries-old forgotten underworld lies beneath Malta.

A hidden tunnel of bones in one of Malta's oldest churches.

Architecturally stunning library serves as the hub of Finnish scholarly life and culture.

One of the most historic cemeteries in Quito is an eclectic mix of architectural styles and famous tombs.

Immortal combat in a Moscow museum.

These "anatomical machines" are only one of the many strange items in this Italian crypt.

This shining multicolored metro station deep under Naples is said to be the most beautiful in Europe.

Commonly acknowledged as the only public monument to the Devil himself.

An ancient Egyptian temple in the middle of Madrid, Spain.

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

In a city that boasts four separate inclined cable railways, this is one of the busiest funicular lines in the world.

The Neapolitan Cult of the Dead still cares for the skulls at this mini-Fontanelle.

Every day is like Christmas on this street where the traditional Neapolitan nativity scene comes to life.

The last moments of the ill-fated Pompeiians, frozen forever in plaster.

San Gennaro, the patron saint of Naples, greets pedestrians between these narrow city streets.

A labyrinth of ancient tunnels hidden below the city holds the ruins of 2,500 years of history.