On the southeastern side of Butler County, about an hour northeast of Pittsburgh, is a delightful bike trail, the Butler - Freeport Community Trail, which runs 20 miles through a scenic wooded valley, along the corridor of the diverse Buffalo Creek Watershed.
The trail offers a level, natural crushed limestone surface with a gradual uphill grade as it travels north and the converse downhill grade as it travels south.
As with all rail trails, the Butler - Freeport Community Trail started as a branch of the Western Pennsylvania Railroad between Butler and Freeport. The line primarily transported the quality limestone deposits needed by the growing Pittsburgh steel industry, but construction of the line opened up the entire region to growth and travel.
Although our ride was cut short because of a malfunctioning brake (so yeah, only rode about two miles of the trail, for a total ride of a much-too-short 4 miles, instead of the 10- or 12-mile round-trip we were hoping for), I'm putting this rail trail on my must-ride list because of cool ruins that still linger along the trail.