Improved door assemblies and related methods of use are provided. More particularly, the present disclosure provides advantageous systems/methods for the design and use of door assemblies configured to mount with respect to a mounting structure associated with a rack or the like. The present disclosure provides for mechanisms for mounting, opening, closing and releasing a door assembly relative to a mounting structure. The present disclosure provides for a rack-mounted door assembly having alternative pivoting axes. Exemplary door assemblies of the present disclosure are configured so as to be simultaneously hinged at the left and at the right, and to permit easy opening from either the right or left, as well as to allow for the complete removal of the door from its mounting structure.