Wikipedia: Regicides Trail is a Blue-Blazed hiking trail, about 7 miles (11 km) long, roughly following the edge of a diabase, or traprock, cliff northwest of New Haven, Connecticut. It is named for two regicides, Edward Whalley and his son-in-law William Goffe, who signed the death warrant of King Charles I of England. Upon the restoration of Charles II to the throne and the persecution of the regicides, the pair hid in Judges Cave near the south end of the trail in 1660.
A poster on our old website added:
Regicide Trail Northern Terminus (approx.) ~ Lat: 41.406883140049985, Long: -72.94149934995517
Regicide Trail Southern Terminus (approx.) ~ Lat: 41.33246548455779, Long: -72.96180501330241
And Neil Clauson added:
The run, which has become somewhat of a Thanksgiving tradition for me over the past few years, can be viewed below:
I ran it connecting in from the Hill Street trailhead. It's about a half mile climb up to the Regicides where I started my watch. There are a zillion ways to link into the trail. For a person coming from out of town, the most logical way might be to park at the southern end of West Rock, the southern terminus of the trail. The northern end of the trail is where it connects to the Quinnipiac trail after a nasty traprock climb. As Rafael indicates, I created a Strava Segment there but I'm not sure how accurately I pinpointed the start/end points.
I have a lot to say about this oddball trail, so please excuse the ramble to follow. First of all, the trail has some really cool history. It's name comes from three judges, or regicides (Dixwell, Whalley, and Goffe), who signed the death warrant for the beheading of King Charles I. The judges ran for their life to New England and hid in the cliffs and caves of West Rock where they were supported by local farmers. The trail also constantly crosses over an abandoned road named after former Connecticut governor Simeon Baldwin. It's closed off and in dilapidated condition, yet for some strange reason it's almost always plowed in the winter!
The trail follows a south/north traprock ridge which is incessantly technical, consistently laden with traprock. It doesn't feel very hilly at all, with the exception of the notches in the ridge at the northern and southern ends. There are very few points where you can open up a full stride. Mostly it's just rock-hopping the whole way. I like running this trail in the winter the most. It is really hot in the summer because of the southwest exposure, there is no water for the dog, and weeds hide the rocks. The trail is very well-marked but not well-trodden. Don’t expect to see many people out there. You might see some rattlesnakes if the weather is right.