The trail up North Mountain is called the National Trail. The full trail is a loop that goes up one side of the mountain and down the other. One side of the trail is closed and is being widened into a road. However, you can still hike the other side as an out and back.
The trail is relatively short (about 1.3 miles RT). It is also steep, about 700 feet. One section had an average gradient of about 27% for 0.3 miles, so even given its short length, it was a fairly tough hike. Trail condition was not great. In a lot of spots, there are small stones which makes it a little slippery coming down (these can be seen in some of the pictures posted). I would definitely wear good boots and I am glad I brought my poles. Because of the trail condition, I would call the trail moderate to difficult.