A structure to be monitored for damage and a method of monitoring the structure for damage are provided. The structure has a coating thereon, the coating defining a surface having characteristics which vary in a predetermined manner with damage to the structure. The surface has a series of conductive tracks applied thereto and in intimate contact therewith such that the said predetermined variation of the surface characteristics will vary the resistance of the series of conductive tracks in a predetermined manner in order to determine both location and extent of damage.