An alleyway plaque is all that remains of the independent Texas' envoy that forgot to pay their rent for over a century.

This 1920s Dutch barge is now a floating bookstore.

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

This shop and gallery is a modern-day cabinet of curiosities, unassumingly positioned along an urban thoroughfare.

A charming 17th-century alley is lined with secondhand bookstores and antiquarian shops.

One of the few remaining casualties of the London Blitz, this destroyed church has become an enchanting public garden.

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

Social saloon from a scrapped trans-Pacific 19th century steamer.

This castle was once considered as an option for the Royal Family's alternate residence, but you may know it better from the 'X-Men' movie.

This small and often-overlooked museum holds some of Spain's finest artistic treasures.

An ancient Egyptian temple in the middle of Madrid, Spain.

Over two centuries old and counting, Madrid's massive botanical garden contains one of Europe's only desert environments.

Madrid's romantically ornate crystal palace has been offering shelter to plants and art for over a century.

The former 1920s mansion of a prominent Catalan developer was used as the Soviet Embassy during the Spanish Civil War, and there is still a bunker below the garden.

A once-secret library of Freemason history in Catalonia.

The studio of Catalonia's most famous theatrical designer remains exactly as he left it.

This cafe offers a curated collection of treats and tipples made by monks and nuns.

Some of the greatest minds in the history of Hungarian art and science converged in this café.

A 19th century artistocrat's mansion, turned into a library, hidden in a modern library.

This Hungarian castle was built out of cardboard and wood until it proved so popular that it got upgraded to stone.

Built in 1870 at the bridge that connected Buda and Pest, this spectacular incline railway was almost lost forever during World War II.

A series of caves under Castle Hill that once held the prisoner Vlad Tepes, better known as Count Dracula.

A hidden church in a hidden courtyard tells the story of the Miracle of Amsterdam.

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