Large white illuminated oval shape above city of BostonTraveling up the expressway into Boston, my girlfriend and I noticed a large oval object in the sky. It appeared to be somewhat transparent and illuminated white lights. After seeing the object we tried to figure out what it was. I thought it might be a blimp. We pulled over to investigate further. It appeared to hover very slowly across the horizon. Upon inspecting this object it couldn't have been a blimp. It was almost as if it were in a haze of white light, it did not appear to be solid or opaque like a blimp would be. It eventually ended up hovering just above the high rise buildings in Boston as though it were further beyond the actual city towards the North Shore. There is an airport around that area as well. We tried to drive into the city to see it better but once in town the buildings obstructed our view. We observed it for about ten minutes.