Hidden beneath the streets of London is a secret subway that only carried mail.

This chilly Canadian hotel has a four-month lifespan due to the unusual material it's made of.

This lovely, if imposing, piece of Canadian gothic is possibly the most photographed hotel in the world.

This former prison now houses a lovely library devoted to Quebec's oft-maligned English-speaking history.

City law dictates that this mountaintop cathedral containing the heart of a saint is to remain the tallest building in town.

A grand Gothic Revival basilica with stained glass depictions of Montreal's religious history has only one soul resting in its crypt.

Montreal's giant farmer's market is a foodie's best friend, especially in the winter months.

A historic Montreal market that was the city's agricultural hub for over century.

Two adjoining collections of 19th-20th century physics apparatuses and instruments.

Dublin's "Dead Zoo" serves as a window to Victorian museum design.

An ancient neolithic tomb that only sees the sun twice a year.

This 30-foot pile of rocks may be the grave of a mythological Irish queen.

Hear the quietest sound from across the dome.

The quaint little store that is said to have inspired a famous Dickens novel was only given its name after the book was released.

These tombs were built into the side of a mountain so that ancient angels could reach the dead.

Roman ruins top white travertine terraces formed by ancient hot springs.

A Turkish monastery tucked into a cliff wall.

A Lycian city of the dead carved into the hillside of Southern Turkey, complete with startlingly human touches.

A book bound in the skin of an infamous criminal, along with countless other specimens.

One of the oldest scientific gardens in Britain, containing more than 13,302 plant species in its core collection.

This castle was established by the 4th Duke of Montrose and is connected to the Buchanan Clan.

The gorgeous library at Trinity College is home to remarkable treasures of Irish identity.

A cluttered and astounding collection of antiquities and curiosities.

Memorial to the Titanic engineers that died working to hold back the sea.