Mastic is the dried tears of Pistacia lentiscus, the mastic tree, cut into the bark each summer so the resin bleeds out and hardens on the ground. The variety that does this generously, var. Chia, grows in many warm places, but only in the southern tip of Chios does it produce in earnest. Botanists still argue about why. The result is that Chios mastic holds a Protected Designation of Origin, the same legal shield that guards Champagne and Parmigiano. From early summer to mid autumn, you can still watch the harvest by hand, the white granules collected grain by grain, sieved and cleaned and sorted the way they have been for centuries.

The roughly two dozen Mastichochoria were not laid out for charm. Under Byzantine and later Genoese rule, they were engineered to defend the island's most valuable crop. The outer houses turn their backs to the world, their walls forming a continuous perimeter with no openings at ground level. Inside, the streets coil into a deliberate maze, narrow enough to confuse a raider and easy for defenders to seal. Some entries once relied on ladders that could be pulled up behind you. Mesta is the most complete of these strongholds, a village you enter and immediately lose your bearings in, every alley folding into the next.

Then there is Pyrgi, where defense gives way to dazzle. Nearly every facade is covered in xysta, a technique found nowhere else in Greece. Builders coat a wall in dark plaster, whitewash over it, then scratch the white away in patterns, triangles, rhombuses, fans, zigzags, until the whole village wears a kind of geometric tattoo. Walk through on a bright afternoon and the alleys seem to vibrate with black-and-white pattern, balconies hung with strings of drying tomatoes adding the only red. A small Museum of Mastic outside the village tells the rest of the story, how this strange resin shaped everything around it.

Mastic is not just harvested here, it is eaten, drunk, and chewed. The resin flavors a spoon sweet called ypovrychio, literally submarine, served as a white lump submerged in a glass of cold water. It scents the local ouzo and a sweet liqueur that carries its own protected status. Chewed raw as the gum ELMA, it gives the faintly piney taste that named chewing gum in the first place, the word mastic shares a root with masticate. Beyond the villages lies the shore: Mavra Volia, a beach of black volcanic pebbles instead of sand, where the dark stones meet improbably clear water.