Mykonos has a strict colour code that requires doors and windows to be painted blue, green or red. This dates back to a tradition where sailors used to paint their doors blue, farmers painted them green and everyone else used red.

The iconic blue doors and shutters of Mykonos and the broader Cycladic islands have both a practical and a historical origin. Originally, the blue color came from a cheap, accessible cleaning agent called "loulaki," which was a blue powder used by locals in their laundry. When mixed with lime (used to whitewash the houses), it created the vibrant blue paint we see today. Historically, the use of blue and white was also a subtle act of political defiance. During the Ottoman occupation and later periods of unrest, Greeks were often prohibited from flying their national flag; in response, they painted their entire villages in the flag's colors (blue and white) as a silent symbol of patriotism. Furthermore, there is a traditional belief that the color blue (resembling the "Evil Eye" or mati) helps to ward off evil spirits. In 1974, a government decree actually made the blue-and-white color scheme mandatory for aesthetic consistency across the islands. While that law has since been relaxed, the "Mykonos Blue" remains a point of pride and a primary driver of the island's world-famous architectural identity.