Swallow migration

People watching at 8Th & Fig, Downtown LA, parked in front of the Corner Bakery. I had been w---wait, this IS the long version! I looked up and saw hundreds and hundreds of small birds circling and performing aerobatics up along the face of the white building which is 777 Figueroa. It was weeks before I realized what I was seeing ( I am only now beginning to learn a little about birding) and I wish that I could go back to that time with the knowledge I have now of the distance and time involved. Even ignorant as I was, it was a spectacular site: the evening rush hour human crush operating parallel to this avian marathon.