This beautiful Victorian ironwork masterpiece was built to keep London from smelling like poop.

The remains of Crystal Palace Great Exhibition of 1851.

The signs of a long buried road can still be found hidden beneath a London sewer grate.

A subterranean ice warehouse that has lain hidden beneath central London for over a century is now open to the public.

This functional solar system model was inspired by the famous Eisinga Planetarium.

A 1:42 scale model of the world's second largest lensed telescope.

When this 18th-century observatory's meridian was moved, it set Sweden's time back by 0.04 seconds.

This octagonal cottage is the smallest and the oldest council house in the United Kingdom.

This abandoned gun tower was built to defend the River Thames from a French naval attack.

Started as a kitchen garden, now the second largest botanical garden in the world.

This sprawling Belgian fort was once thought of as impenetrable but now it is simply an abandoned relic.

A garden of flying flowers.

You would never come across this tiny green oasis if you didn't know it existed.

An early 20th-century sanatorium, long abandoned and now being reclaimed by nature.

This bike path was sunk below water level for maximum wonder.

This bike path traverses the treetops.

The world's tallest boat lift stands as a massive piece of industrial tourism.

What was once a bustling mining installation is now a bustling hub of contemporary art.

This collection of solar timekeepers includes the world's first digital sundial.

Dummies recreate radiological discoveries from history.

The patron of this extravagant Art Nouveau confection insisted that nothing less than a boat should project from its facade.

The Belgian royal family's private depot now stands abandoned and forgotten alongside the tracks.

This whimsical statue dumps water on its head to symbolize knowledge flowing into his brain. Or maybe booze.

Housing the groundbreaking maps and globes of Gerard Mercator.