Rock Circuit Trail, Middlesex Fells (MA)
This is an established route in the Fellsway with well-marked blazes that travels in a loop around a series of summits in the eastern part of the park. This is arguably the most challenging trail in the Fellsway with lots of up and down and technical footing. The course touches on about a dozen viewpoints, passes next to a waterfall and features several really fun scrambles with a lot of rocks and roots on the flatter sections.