Mario, when we visited Caramulo I didn't notice an alternative route from the top of the hill back to the museum. I don't recall there being that much space at the top. Are the cars held up there and return to the museum in a convoy? As it was raining hard we didn't linger there.
I also don't recall there being any space near the roadside for spectator viewing. Is most of the action around the start line and the museum?
