Built entirely of interlocking pieces, construction of this Chinese Muslim house of worship required zero nails.

Lonely minaret stump of a destroyed city.

Tiny communists hammer away on the Olomouc Astronomical Clock.

This memorial park stands on the site of one of the largest mass executions of the Second World War.

A Red Cross memorial museum at the site of the Niš concentration camp that operated for four eventful years during World War II.

Structure built from the skulls of vanquished foes.

The bizarre rocks of Đavolja Varoš are the result of natural erosion.

A towering spire in the fortress of Kalemegdan honors the victorious armies of Serbia during their struggles against the Ottoman Empire.

Nikola Tesla's ashes are held in a golden sphere, surrounded by his works.

In the hinterlands of Serbia's capital, a giant reflective mushroom houses an aeronautical history of the former Yugoslav republic.

This hanging crocodile is thought to be the "dragon" that once plagued a Czech city.

A peculiar clock commemorates a historic victory won by ringing the noonday bell an hour early.

Europe's second largest ossuary wasn't discovered until 2001.

Oriental bazaar in the heart of Sarajevo.

A huge wooden clock that is so beautiful its creator was forcibly blinded.

A floundering Polish shipyard was once the soul of the Solidarity movement that capsized communism.

The silly symbol for an underground protest group is now scattered around the city.

This unusually shaped mountaintop tower looks like a UFO floating over the city.

An enormous and lavish Gothic church in Czechia.

A massive 1830s industrial site once known as Czechia's "Iron Heart" has been transformed into a playground of science, technology, and art.

An ornate plague column – built to celebrate life – claimed the lives of numerous artisans during its construction.

The deepest sinkhole in Central Europe comes with a grisly tale and an unusual nickname: “The Stepmother Abyss.”

The sanctuary holds what was once believed to be the saint's incorruptible tongue.

This network of conjoined cellars was riddled with traps and supposedly allowed the townspeople to pretend their homes were deserted.