Clementinum

The Jesuits who built the Clementinum were not modest people. They arrived in Prague in 1556 with almost nothing, according to legend just a single book, and within 170 years had raised this enormous complex, filled it with 27,000 volumes, and commissioned that 68-meter tower you can see above you, crowned with a bronze Atlas carrying the weight of the heavens on his shoulders. Mozart himself once played the organ in the Mirror Chapel inside.

But the story that lingers here is darker. When Pope Clement XIV dissolved the Jesuit Order in 1773, the brothers refused to hand over the gold and manuscripts they had spent two centuries collecting. They hired a mason, blindfolded him, drove him through the city for hours to confuse him, and had him wall up a secret chamber somewhere deep inside these walls. They paid him generously. They also cursed him: if he ever spoke, he would go blind and his soul would be damned.

Years later, a reward was offered, and the mason talked. The authorities searched every corridor and found nothing. Shortly after, the man went blind, and when he died, they say his soul never left. He is still here, wandering these halls forever, searching for treasure he can no longer see.

Which, honestly, makes him the world's most committed security guard.