A 16th-century Andalusian palace.

This nightmarish children's plaything was left grotesque to help kids conquer their fear.

The remains of this ancient fortress atop a manmade hill look as though they were built into a volcano.

A massive, heart-shaped, wind-carved crater in the middle of the Israeli desert.

A magical oasis in the middle of the Negev Desert.

Deep in the Negev Desert, the world's tallest solar tower looks like a sight straight out of science fiction.

This colorful and quirky set of pegasus sculptures celebrate the works of poet Zbigniew Herbert.

A tribute to the Polish insurgents who fought in the failed attempt to end their city's Nazi occupation.

Atop this library is one of the most beautiful green spaces in Warsaw.

Amsterdam's narrowest house facade is a monument to 17th-century tax evasion.

In the days before house numbers, these colorful signs held clues about various buildings' purposes.

The former home of a mad diplomat is said to still be marked in bloody, arcane scrawls.

Amsterdam's former hotspot for public executions and dissections.

Three connected pink triangles memorialize persecuted gays and lesbians throughout history.

This museum inside Amsterdam's largest cemetery explores how people deal with death.

A beautifully eclectic mix of architectural styles.

A Dutch passageway's artistic, aquatic-themed makeover pays tribute to the capital city's famed waterways.

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

This gorgeous reading room houses the oldest and largest art history library in the Netherlands.

A curious collection dedicated to human and animal anatomy and pathology.

The world's first zoo for microbes collecting the horrible and wonderful things living on and around us.

Cat art as far as the eye can see.

Established in 1638 to battle the Black Death, this botanical garden is a treasure trove of rare flora.

A floating cat sanctuary on an Amsterdam canal.