Hidden in a grotto 26 feet below Nottingham's oldest hotel, this stylish subterranean drinking den is notoriously hard to find.

Remnants of a Victorian garden feature sitting in public woodland.

London's smallest police station is barely the size of a phone booth.

Shiny Brutalist box commemorates a pioneer of electricity and houses a railway transformer.

The Tudor-style cottage in the middle of the square is not quite what it seems.

Installed at a chaotic intersection, this gave London traffic cops a place to hang their heavy woolen coats.

A plaque marks the underground site of one of London's "lost rivers."

An easily overlooked stretch of ornate window fronts and gaslight lamps that could be right from the pages of Dickens.

A late-medieval Dutch castle with trick fountains in its whimsical water gardens.

This ruined medieval castle was the scene of Lord Robert Dudley’s seductive reception for Queen Elizabeth I.

This giant urban staircase was built to keep the city's brave fighting men from getting waylaid in the red light district.

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

This beautifully designed star-shaped fort was the premier defense system of the late 1500s.

The last working windmill in the U.K. that has eight sails.

These bleak 800-year-old ruins were once the royal residence of choice for hunting in Sherwood Forest.

A forest of immensely tall and unusually straight oak trees planted nearly 200 years ago to build naval ships that never came to be.

A magnificent mansion hides a delightful collection of historic timepieces.

Lord Byron's embalmed body lies within this medieval church.

A vast overgrown cemetery, once known as one of London's "Magnificent Seven."

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

This ornate Victorian marketplace was the setting for Diagon Alley and the Leaky Cauldron in the Harry Potter films.

The rose garden in Regent's Park where Pongo and Perdita met for the first time in Disney's "101 Dalmatians."

A historic hill of tall tales, with one rather special tree.

This 2,000-year-old tree inspired the nursery rhyme "Rock-a-bye Baby."