I was on my balcony, having a sigaret, when i unexpectedly saw the fast moving triangular object in the sky. I immediatly thought that it is not an airplane, besause it didnt have any similarity to aircrafts i have seen so far. It was very quiet windless night and there was no noise from the streets. Still i didnt hear any sound from the object. It felt almost ghostly. Streets were brightly lighted and the object was flying only 100-200 meters above the ground (streetlights were reflecting from it like they reflect from the clouds), so i had clear view of the object. It was the size of a large airplane. It was a perfect black isosceles triangle with straight sides. On every angle it had smaller triangle shapes in gray color. It had no lights and i had strong feeling that i was not ment to see it. I saw it only for approx 10 seconds, after that it disappeard behind the buildings. After it disappeard, i searched the internet, hoping to find similar sightings, but i could'nt find the exact match.I also add my sketch of the UFO and excuse my poor english.