A monitoring system for monitoring an Unmanned Aerial Vehicle, the monitoring system comprising: - a mobile communication system comprising at least three base stations (BSs) (201, 202, 203), each BS configured to receive a respective radio signal (301, 302, 303) from the UAV, wherein the mobile communication system is configured to determine a first position of the UAV based on triangulation of the radio signals (301, 302, 303) received at the at least three BSs (201, 202, 203) with respect to their received signal strength or based on cell identification of at least one of the BSs (201, 202, 203), wherein the mobile communication system is configured to connect with the UAV to receive camera data from the UAV, the camera data indicating a ground picture recorded by the UAV - a localization system configured to verify the first position of the UAV determined based on triangulation or cell identification with a second position of the UAV determined based on the camera data, characterized in that the localization system is configured to: open a sector map of a geographical region (211, 212, 213) of the at least three base stations (201, 202, 203) based on the first position of the UAV, and determine the second position of the UAV based on a map section indicating a local environment of the first position or based on a map section around the BS of the at least three BSs (201, 202, 203) which receives the strongest radio signal from the UAV, by identifying at least one landmark from the map section in the ground picture as a reference location and by a.) determining a distance of the UAV to the at least one landmark based on a camera zoom factor with respect to a size of the ground picture and a size of the map section, b.) determining a ground coordinate of the UAV with respect to the at least one landmark based on a camera angle and c.) determining an altitude of the UAV based on the determined distance and ground coordinate. - a mobile communication system comprising at least three base stations (BSs) (201, 202, 203), each BS configured to receive a respective radio signal (301, 302, 303) from the UAV, wherein the mobile communication system is configured to determine a first position of the UAV based on triangulation of the radio signals (301, 302, 303) received at the at least three BSs (201, 202, 203) with respect to their received signal strength or based on cell identification of at least one of the BSs (201, 202, 203), wherein the mobile communication system is configured to connect with the UAV to receive camera data from the UAV, the camera data indicating a ground picture recorded by the UAV - a localization system configured to verify the first position of the UAV determined based on triangulation or cell identification with a second position of the UAV determined based on the camera data, characterized in that the localization system is configured to: open a sector map of a geographical region (211, 212, 213) of the at least three base stations (201, 202, 203) based on the first position of the UAV, and determine the second position of the UAV based on a map section indicating a local environment of the first position or based on a map section around the BS of the at least three BSs (201, 202, 203) which receives the strongest radio signal from the UAV, by identifying at least one landmark from the map section in the ground picture as a reference location and by a.) determining a distance of the UAV to the at least one landmark based on a camera zoom factor with respect to a size of the ground picture and a size of the map section, b.) determining a ground coordinate of the UAV with respect to the at least one landmark based on a camera angle and c.) determining an altitude of the UAV based on the determined distance and ground coordinate. open a sector map of a geographical region (211, 212, 213) of the at least three base stations (201, 202, 203) based on the first position of the UAV, and determine the second position of the UAV based on a map section indicating a local environment of the first position or based on a map section around the BS of the at least three BSs (201, 202, 203) which receives the strongest radio signal from the UAV, by identifying at least one landmark from the map section in the ground picture as a reference location and by a.) determining a distance of the UAV to the at least one landmark based on a camera zoom factor with respect to a size of the ground picture and a size of the map section, b.) determining a ground coordinate of the UAV with respect to the at least one landmark based on a camera angle and c.) determining an altitude of the UAV based on the determined distance and ground coordinate. a.) determining a distance of the UAV to the at least one landmark based on a camera zoom factor with respect to a size of the ground picture and a size of the map section, b.) determining a ground coordinate of the UAV with respect to the at least one landmark based on a camera angle and c.) determining an altitude of the UAV based on the determined distance and ground coordinate.