The enigmatic sculpture hides above an escalator in a Milan metro station.

An ancient artistic garden parlor full of hidden water wonders.

An open-air museum in a mountain valley features works designed to blend in with—and disintegrate back into—their natural surroundings.

This centuries-old Italian chapel hangs midway down a sheer cliffside.

A complex, nine-layer maze on the grounds of a Venetian doge's playground.

Thousand-year-old Viking runes adorn an ancient Greek lion at the entrance to the Venetian Arsenal.

A sinister pyramid in the Frari contains the heart of the famous neoclassical sculptor.

Geothermal waterfalls in Tuscany.

This curious building hides eclectic details like medieval gargoyles alongside naked angels and Art Nouveau mosaics.

Long-abandoned art nouveau baths beneath Milan's Piazza Oberdan.

This 6th-century church has the largest and best-preserved collection of Byzantine mosaics outside Constantinople.

Filled with goldfish swimming in a shallow pool of sea water, this ancient crypt is more wishing well than burial site.

Old batteries and frog skeletons reside in this lakeside monument to Alessandro Volta.

This 1st-century CE Roman bath sits under a carpark.