A memorial dedicated to victims of the Irish Potato Famine who perished while quarantined on this island.

This ambitious father and son team reigned supreme over the North End, and witches, for many years.

A morbid secret lies hidden within the beautiful walls of the Boston Athenaeum.

This Boston medical museum features the skull of the famous medical case of Phineas Gage.

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

This early version of the guillotine was used to execute the man responsible for its construction.

The 16th-century church has the only stained glass windows that survived the Scottish Reformation intact.

These steps offer a breathtaking view of one of Europe's most besieged fortresses.

Overlooked by many, the two famous Scottish warriors guard the main gate of Edinburgh Castle.

A verdant 17th-century-style garden hidden along Edinburgh’s Royal Mile.

A beautiful Greco-Roman structure houses a well once believed to have healing powers.

One of the oldest scientific gardens in Britain, containing more than 13,302 plant species in its core collection.

The taxidermied remains of Charles Dickens' pet raven, which helped inspire one of Edgar Allan Poe's most famous poems.

The beautiful baroque library of the Hapsburg empire.

The bears may be gone, but their old cages can still be found.

One of seven Jewish catacombs in Rome and one of only two open to the public.

One of the most important yet well-hidden museums dedicated to the history of medicine.

This former Roman Catholic Church still contains the embalmed hearts and organs of 22 popes.

The martyr's wax-enhanced skeletal remains lie preserved in a glass case in the Santa Maria della Vittoria in Rome.

The skull of the patron saint of lovers lies in the Basilica di Santa Maria in Cosmedin—maybe.

Hundreds of lucky felines haunt the ruins where Caesar was murdered.

This nearly endless university hallway is home to a unique sunset known as "MIThenge."

This sculpture commemorates Edinburgh's sister city and their respective celebrity dogs.

This 16th-century house tells the city's history through old artifacts and quirky tales.