The tunnel is just south of Grand Central, in the 30s. There is apparantly some kind of sound exhibit in there. But, when I found that you couldn't ride through, I lost interest.

While I'd love it if the event went past 1pm, I wouldn't say that the 7am start is too early. It seems to me that bike-lovers tend to start early. I am on the road by 5:00 or 5:30 on every weekend morning and on any weekday that I take off from work in order to ride (despite the fact that I am by nature a night person).