Wikipedia: The Timberlin / Metacomet Loop is ~14.3 miles in total with approximately 2,400 feet of elevation gain that connects the tougher parts of the Metacomet Trail going up and over Castle Craig in Hubbard Park, with the 4.8 mile Blue / Red Timberlin Trail. Starting from trailhead on Orchard Road, the loop begins at the southern end of the trail portion of the blue-blazed Metacomet trail, and follows the Timberlin trail north through Bicentennial Park, then west through Timberlin Park before intersecting with the Metacomet. Taking the Metacomet south, there is a short road stretch on Edgewood Avenue before starting the technical climb up to Castle Craig. The trail descends and follows the blue-blazed Metacomet trail back to the start of the loop.
Stefan Rodriguez adds:
This section of the Metacomet is part of the New England trail located in central Connecticut and has a little of everything: mud,small water crossings, traprock, ledge walking, steep climbs and descents, and VIEWS—most notably, a view from Castle Craig at the top of East Peak.