The four landings commemorate a royal visit to Europe's biggest observatory.

These old towers extract salt from the sea.

This whimsical, unique clock has been entertaining shoppers for well over 20 years.

A museum and gardens with unusual plants and a history of progressive programming for the blind.

A saintly relic hidden in a Prague church basement.

This artificial cave looks like something out of a fairytale.

Despite attempts by local police to discourage it, Beatles-inspired graffiti has been a means for artists to air grievances for decades.

Two stunning 17th-century libraries and a cabinet of curiosities.

The history of occult science is turned into a creepshow at this lurid Prague tourist attraction.

Real bones which are said to have belonged to a Polish dragon.

This Polish cave has housed a dragon, a brothel, and an enduring legend.

At first glance, this area seems like just another city park, but the lush landscape hides a dark past.

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 first ‘Harry Potter’ film.

This sprawling concrete suburb of Kraków was designed by the Soviet Union as the model proletarian city.

Reminders of the Battle of Berlin still scar the railway.

Metro station with a claim to rock n' roll fame.

Neon artworks light up this dark Edinburgh tunnel.

The final resting place of soldiers' loyal canine companions.

A six-ton wedding present for the King of the Scots.

360° views of the city plus five floors of optical illusions and hands-on science.

This 17th-century street hidden beneath Edinburgh was once a breeding ground for the black death.

The taxidermy remains of the first mammal ever cloned from an adult cell are on display in Edinburgh.

There are plenty of wonderful panoramic vistas in Edinburgh, but not many are hidden smack in the middle of the Old Town.