Various embodiments of a monument cap device are disclosed. In one embodiment, a monument cap comprises a circular lid with a first sidewall along its circumference; a second sidewall protruding from a bottom face of the circular lid, the second sidewall having an outer diameter that is smaller than an outer diameter of the first sidewall; a plurality of legs extending from the second sidewall for engaging with an opening; and a plurality of brace members each extending between one of the plurality of legs and the bottom face.