Sweden's largest optical telescope sits on a rooftop in Stockholm.

The Swedish flag over this small naval fort signals that the nation is at peace.

Outside a Viking museum sits a modern-day runestone made by a Swedish runemaster using traditional methods.

It is said that each of the white stones in the red facade of this medieval house represents the head of a murdered Swedish noble.

Stockholm's narrowest alley is barely over two feet wide.

One of the world's first dedicated bank buildings in the world is now the oldest one.

This gem from the industrial age helps visitors and residents alike traverse hilly Stockholm.

It houses the remains of a 17th-century version of the Titanic.

A rare surviving cluster of 1950s tenement buildings were saved from demolition after featuring in an award-winning film.

The world’s second-largest flood defense barrier has protected London for decades.

The oldest floral clock in the world still functions today.

This monumental neo-Renaissance tomb in Vyšehrad Cemetery is the final resting place for Czech cultural legends.

The ground on which Shakespeare’s initial playhouse once stood.

One of the four clock faces on this church is mismatched, in a nod to a historic slight.

A pre-war mansion that survived the modernization of Athens.

This garage is frozen in the late 1990s, full of rare and untouched cars and motorcycles.

An 18th-century hunting lodge turned haunted Baroque palace.

These lesser-known Maltese catacombs date back over 1,700 years.

Burial grounds for more than 1,000 bodies deep under the modern town of Rabat.

Spectacular secluded inlet with clear waters flanked by limestone cliffs.

Spitfire airplanes with butterfly wings hover over Prague’s skyline.

A seemingly abandoned store in central Manchester with a lengthy backstory.

A one-of-a-kind shopping mall dedicated to Buddhist and Daoist spirituality.

These enormous concrete blocks played a vital role in one of history's most important days.