Twin Peaks is located in the geographic center of San Francisco. These distinctive hills are not only recognizable landmarks with spectacular views, they also play a major role in the safety and security of San Franciscans. Towers on Christmas Tree Point provide communication support to the police and fire departments. Firmly constructed into the bedrock of Twin Peaks are three massive municipal reservoirs that supply gravity-pulled drinking water and water for fire fighting. Roads and a tunnel were built on, around, and through the peaks with the purpose of gaining easier access to the western parts of the city. Farms and homes appeared along Corbett Road, and new neighborhoods sprang up on the slopes of Twin Peaks: Midtown Terrace, the Crown, Graystone, Villa Terraces, and Clarendon Heights, on which stands the Sutro Tower.