Celtic v Porto in Seville.
The whole occasion was phenomenal I don't think I have ever seen so many Celtic fans in one place at the one time.
Was living in Spain at the time and the congregation of Scots on the south coast was nuts. I was in Malaga and there were randoms rocking up with no ticket and no hotel, just sleeping on the beach in the build up to the match. I didn't have a ticket but travelled up to Seville and watched it on a big screen in a park. Lively night!