The old city is surrounded by walls, and the streets are arranged in a herringbone pattern allowing free circulation of air but protecting against strong winds. Korčula is tightly built on a promontory that guards the narrow sound between the island and the mainland. Building outside the walls was forbidden until the 18th century, and the wooden drawbridge was only replaced in 1863. All of Korčula's narrow streets are stepped with the notable exception of the street running alongside the southeastern wall. The street is called the Street of Thoughts as one did not have to worry about the steps.