Square object with small wing-like pertrusions out of sides, flew directly above house, not higher than 500 ft., past dusk, no lights, no sound. it looked to be about the 100' x 100'. i am due north of dia and watch air traffic into and out of the airport at least 15 times a day and night while i smoke. i count them, i watch their flight paths and exhaust trails. some come so low during bad weather that i think i should have gone to the bathroom first. i've seen thousands of military, emergency, private and commercial aircraft over me, even drones. i like to estimate sizes and altitudes and directions they are going in relation to the us and local airports and the altitudes of the planes. this, was different, and i would like to know if there are any military drone exercises or reports of aircraft in distress because of electric failure. not having any lights is the most intriguing part of this. no sound, meant it could have been a drone, but any drones flying that close to dark, should have had lights. i watched it fly from over my house, straight to the west for about 2 min. until i couldn't see it any more. it showed no signs of distress, made no changes in it's path, went very slowly, and didn't make a sound.