A very large, round aircraft, that was hovering over houses.

I saw a large, round object, hovering in the sky. The object was some kind of aircraft. It was hovering relatively low, at around the height that a helicopter would hover. There were lights spaced out around the edge of the underside of the aircraft.
I also saw several lines on the underside of the aircraft. The lines were both horizontal and vertical, they looked like dividing lines that were going into the (what seemed to be metal) underside. The large round aircraft made no sound. It hovered for several seconds, and then suddenly disappeared.