Ascutney is one of the hardest climbs you'll find anywhere. It features a monotonous gradient of around 12% and gains more vertical in the first 1.5 miles then just about any other climb in the country. Most cyclists will find that you need special gearing to get up this without walking. Personally, my one time going up it felt easier than Okemo, mostly because I had nice low gears for Ascutney, but tried to do Okemo with a 34-29. You will have to pay the toll booth (3 dollars, I think) to go up it, or pay about 35 on race-day.
Ascutney is located in Vermont. It is 5585.4 meters long with an average gradient of 12.4% and a maximum gradient of 18%. Find similar hills.