These red lights are called aircraft warning lights.
Aircraft warning lights are lighting devices that are attached to tall structures and are used as collision avoidance measures. Such devices make structures more visible to passing aircraft and are usually used at night, although they may be used during the day as well. These lights need to be of sufficient brightness in order to be visible for miles around the structure.
These lights can generally be found attached to any tall structure such as broadcast masts and towers, water tanks located on high elevation, electricity pylons, chimneys, tall buildings, cranes and wind turbines. Shorter structures that are located close to airports may also require lighting.
Red lights are commonly found to be used in urban areas, since it is easier for pilots to spot them from above. In general, there are several types of lights that are used worldwide. The International Civil Aviation Organization (ICAO) sets standards, usually adopted worldwide, for the performance and characteristics of aviation warning lamps.