Circular, silent craft with revolving white lights on bottom.

While driving south on the Spaulding Turnpike, my passenger noticed what she called "something very strange" moving in the same direction as us and aparrently matching our speed.  She was only able to see it by putting her face close to the glass and looking up.  Thinking that she was talking about something attached to my car, I pulled off the highway by taking a left exit and pulled into a parking lot, where I found about 25 cars already there with everyone out of their vehicles looking up in the sky.  I got out of the car, but my passenger was too afraid to get out.  She could see the object plainly from inside the car, as it was now huvering over the parking lot.  I could not tell for sure how high it was because it made no noise.  The structure was not completely discernable, but appeared to be round with very bright white lights on the bottom completely around the perimeter.  The lights were sequencing in such a manner as to make a revolving appearance around the bottom of the craft (similar to a marqui sign).  In fact, it may have been only one light blinking and revolving around the bottom of the craft.  The object would huver for approximately one minute, and then move at a very fast speed in a northerly direction, aparrently following the highway until it was out of sight.  When I asked a man in the parking lot "What the hell did I just see?"  he replied something like "stick around, and you'll see it again.  It's been doing this for quite a while!"  I stood and watched with him for a minute, and then the object re-appeared over the highway, moving very slowly from the north until it was over our parking lot again where it huvered.  More cars pulled into the parking lot.  Then it shot away again and I left.