A living memorial to the trees London lost during the Great Storm of 1987.

This intriguing Bronze Age artifact spent centuries hidden within a Welsh faerie hill.

Legend says these colorful, invasive residents are the descendants of birds released by Jimi Hendrix.

The bronze uniforms commemorate the vital role of women during World War II.

These wire animal sculptures commemorate the exotic inhabitants that once called the Tower of London home.

Putting the "mod" in "modular" since 2000.

This open-air mosaic gallery honoring an English artist took hundreds of volunteers more than seven years to create.

Its collection includes a broad array of social, geographic, graphic design, and political history.

The commemorative stone column conceals a secret laboratory.

A unique tribute to the millions of animals who served and died for the British military.

A monument to the thrice mayor of London who according to lore made his fortune by selling his rat-chasing cat.

This pump on the bad side of Victorian London betrayed a horrifying revelation about the water supply.

This coffee shop lies hidden beneath a historic church.

The first geometric self-supporting spiral stairs in Britain are a truly beautiful sight.

This secluded walkway overlooks a magnificently wild London green space.

Artists and musicians now rule over this former rail station.

A closed London rail station created to cart away the dead still bears the marks of attempts to make it less morbid.

The sixth of London's "Magnificent Seven" cemeteries, and a source of unlikely inspiration to Beatrix Potter.

A Victorian natural history and ethnographic museum with wonderful turn-of-the-century, science-book-esque evolution displays.

Rebuilt remains of a temple to Roman god Mithras.

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

The celebrated eyesore created by starry-eyed sweethearts.

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

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.