It was about 1 a.m. I went to exit off the freeway get gas and take a bit of a rest p. I noticed shape cloud but didn't think much of it until I got out my truck then I looked and I notice it wasn't clouds, it had a structure shape squarish almost like a building floating in the sky with a definite blue haze aura or something with a dark blue color illumination below structure. I looked around for others who may have pulled over to view it, but cars kept driving not seeing it. I spotted it coming off exit but didn't think it was anything but low clouds until I got out to rest, then I noticed edges. Stood there trying to see it better for couple minuted then edges seem to buzz, crackle electric effects for couple seconds. Then I was able to see how large or was. Like a single story office bldg, no lights but definite blue area aura below it. Very dark area,in sky due to clouds. Object was beneath cloud cover and about 500ft+ off ground from mountain side. I'd say solid 15min hovering, rotation, tilting then it slowly moved upward away path on side of mountain into cloud cover high up. Very large. Like bigger than Luxor bldg but sqaured off areas. Metal grey surface has grooves curving patterns on side. Could not see topside. Pattern of line grooves like fish hook pattern or semi swirl patterns. Didn't look like a ship, more like a bldg floating. Could have had better view if there was noon light. There look like a possible object behind next to it, I noticed when it started to ascend I saw a second blue aura further back, like miles behind it but too far to see object. I felt curious like trying to solve a puzzle feeling, body feeling was shivers from cold weather. Cars kept driving by the whole time. I had a good fix on it with my eyes so I know it was not cloud shapes that low. No sounds expect a buzzing crackling electric noise for couple seconds and a humm. It rotated slowly. What made it interesting was the tilting as if it was trying to focus or position itself like a satellite dish allignment. But aiming it toward the mountain side, not the sky. Blue aura stayed constant throughout sighting. Ascending path was NW low angle upward into cloud cover. Blue aura diminish once it took flight. Structure was squared with many squares on top and bottom. Sides were large and had swirl grooves or decrotive Patterns. I say decrotive as it seem to be artistic instead of mechanical. Again, very large bldg like floating. Got back into truck thinking my phone camera would have been nice to take a shot but probably too dark. My head feels like I need caffeine all the time up til now. I had only one other encounter when I was living in Honolulu. I saw smaller structure but same metal look and shape falling vertically that almost hit hotel front of Aka Wai. I was sitting on tailgate of my truck bed in harbor lot. That was 8yrs, who.