The Race to the Tower is the toughest of the Threshold series, in my opinion. It is a hilly, very hilly, very very hilly double marathon starting in Stroud and heading up the Cotswolds as far as the Broadway Tower.
It is expensive, £190 for the 2 day marathon with overnight camping, but the route is well laid out, well signposted. The superbly marshalled check points are stocked with everything you need food, drink wide and medically.
This is not a race to take lightly. You need to have trained to attempt any of the alternatives (day one marathon only, 52 mile all the way through, or marathon day one, camp overnight, and marathon day two).
It is tough, in the summer, and even though the CPs are between 5 and 8 miles apart, you run out of water quite quickly. The hills will finish you, and the downs can be technically challenging at times. Especially when your legs have gone.
The route has a bit of everything but you are mostly climbing to the brow of the hills and then being rewarded with stunning panoramic views of Gloucs. You will run beside a few roads, but not for long, through quaint villages, couple of golf courses, but mostly it is the hills and sheep fields.
I would recommend it, even if I am a little put off by the price, and still smarting a little for them screwing up everyone's race tees and series hoodies. But I would still say go for it. Completing the Threshold Series of Stones, King and Tower is perhaps my proudest running achievement to date.