Amid the bustle and noise of the Financial District hides a secluded garden oasis above the city streets.

This beautiful building in the heart of Manhattan's Financial District was empty for decades.

A terrific purveyor of natural history objects and curios.

The world's first zoo for microbes collecting the horrible and wonderful things living on and around us.

The world's only museum devoted to the wonders of fluorescence.

This unattributed sculpture in Amsterdam is hiding in plain sight.

An Amsterdam street lined with antique shops each one dedicated to a different obscure collection.

The attic of a four-century-old canal house hides a clandestine church.

A gargantuan crystal kingdom.

Now nearly dry, this lake is said to be the ancient home of the Lady of the Lake, and was once thought to be bottomless.

The largest greenhouse in the world is home to over one million types of plants.

18th century anatomical amphitheater of the Royal College of Surgery of Barcelona.

A beautiful but toxic fountain of mercury.