For me it is the state cross country meet when I was senior in highschool. Yeaah that far back. It was the Michigan International Speedway, where the yearly Nascar race is run at. The course started in the middle of the in field and went out across the track to the back of the stadium and then finished along turn four at the real finish line for the races. The stands were packed with people and the crowd was really roaring when I crossed the line.
A close second worth mentioning is this year, when I got to run in Las Vegas with MrsMcbeev. We started at the Golden Nugget and made it to the beginning of the strip. Running under the Sahara and Stratosphere was a pretty cool experience, minus the heat I think it was 90 at the time and it was only like 9am.