Large undenible object. 100 feet off the ground. I was right underneth it. The size and shape of a football field.

It was about 10pm. I was camping of sorts on my balcony do to relitives visiting. While I was looking at the moon I saw a very large object. I just saw the bottom at first as it passed over the apartment building I was living in. I didn't know what I was looking at. The first thing I thought as I started to see more and more of the bottom of the craft, is that it was a blimp (having never seen a blimp). I noticed no sound because I could still hear crickets and palmento bugs cherping. The wasn't but maybe 100 feet off the top of the building. Once I saw the entire bottom of the craft it was huge. A massive rectangle in shape, I would say the size of a football field. That is 50 yards in width and 100 yards in length. It was close enough to see that the craft was made of what appeared to be metal. It had semetrical design that's to say I could see long flat "beams" (like I beams used in construction) they kind of criscrossed over the objects' undersurface meeting in a triangel pattern. In each triangle had it's own semitery a circular indentation and a receded light that was not very visible a sort of green in color. As it passed completely overhead and I could see the end of the object I was looking for the balloon part of the blimp and it wasn't there, it wasn't until that moment that I realized it wasn't a blimp. The object was thin at Max. 4 feet in depth. That was when I ran inside screaming there is a UFO outside! I was met with "ya right". By the time I got someone to come outside with me it had moved off so all me and my cousen could see the rear edge of the craft. She said "where is the UFO" I said "it's right there" (pointing at the object as it was moving away) And she said "no it's not" I replied "Do you see something right there?" she says "ya" I replied "That is a UFO"
Date is approximate.  PD