It’s no secret that the Greater Boston area has all kinds of hiking options from easy walks that couch potatoes can do to difficult climbs that will test even the most seasoned hikers. And those who take their hiking seriously often look for “training” hikes in the region that can be used to prepare them for the real-deal stuff a few hours to the north, such as in the White Mountains of New Hampshire or Vermont’s Green Mountains.

I explored one of those training hikes last year—the very challenging Skyline Trail in the Blue Hills just south of the city. Now, it’s time to look at another one just north of Boston in the Middlesex Fells.

While the Fells has its own Skyline Trail in the vast western part of the reservation, I’m more interested in the shorter Rock Circuit Trail in the smaller eastern part of the Fells. The Skyline Trail in the Fells really isn’t that tough, but the Rock Circuit sure is, so much so that if you’re a beginner hiker, the best plan is to train for the Rock Circuit, which will in turn help you train for the real mountains up north.

The Rock Circuit’s a loop (hence the “circuit” part of its name) that runs a scant four miles in length as opposed to the seven miles that the Skyline runs. Unlike the Skyline, however, you won’t find many long stretches of relatively level ground here, and as you might also gather from its name, the path is extremely rocky, testing knees and ankles alike.

There are two popular starting points for the Rock Circuit, with one starting from the Flynn Rink in Medford by the western part of the trail (and the parking lot here is indeed open to hikers), but for the benefit of people without wheels, we’ll focus on starting from the east, which is surprisingly close to the Oak Grove T stop on the Orange Line in Malden and which also has plenty of free street parking on weekends. Leaving the station on the Washington Street side, walking two blocks north, and turning left on Glen Rock Avenue for another two blocks to a right on Elliot Street will get you to the trailhead, which is just after the last house on the left.

The trail that starts from Elliot Street is very short but rather brutal, getting your heart beating right off the bat as it climbs steeply into the Fells. This is not actually the Rock Circuit trail, but by taking a right at the end, then soon taking a left on the blue-blazed Cross Fells Trail, you’ll find yourself meeting up with the white-blazed Rock Circuit trail maybe 15 minutes after first entering the reservation. It doesn’t matter if you take a left or a right on the Rock Circuit (remember, it’s a loop), but for the sake of getting to some of the best parts right away, take a right and you’ll almost immediately start climbing and dropping steeply along Black Rock, which has several viewpoints to the right, including a huge open ledge at the northern edge of the hill that has jaw-dropping views of Boston, Malden, Melrose, Stoneham, and beyond, including Boston Harbor and some hills off to the north. The Rock Circuit descends steeply as you leave Black Rock, soon coming to the head of a gorgeous cascade that has a narrow trail that heads down just before it.

This is an extremely steep trail and can be dangerous when wet, but it’s worth going down it to see the waterfall front and center—and also to look back up at the cone of Black Rock, which from this vantage point really does look like a mountain that’s above treeline.

Returning to the Rock Circuit (if you went down to see the cascade, that is), continue to follow the white blazes and some more relentless ups and downs until reaching Melrose Rock, which has a similar table-like ledge to that of Black Rock and which also has spectacular (and slightly different) views of civilization far below. As with Black Rock, care must be taken here because the rock face basically ends at some steep cliffs, so it’s best to keep a bit of a distance from the edge.

Melrose Rock marks the last of the views for awhile, with the Rock Circuit continuing to climb up and down rocky sections and finally dropping down to the busy Fellsway East, which you’ll cross and then start a modest climb up and over some unnamed hills and ledges. This part of the trail more or less parallels the High Fells Reservoir, a bucolic tree-ringed body of water to the left that can be accessed near where the Rock Circuit Trail eventually meets up with the Wyoming Path and the Reservation Path.

This is a highly recommended breaking point if you want to get off the Rock Circuit for a bit and explore, as a series of interesting trails and fire roads loop around the reservoir, and if you have a map and a good sense of direction, there’s a peninsula that goes out into the water and is a great place to have a picnic or snack break on any number of rock faces overlooking the reservoir.

One of the “easiest” (and yes, take this term loosely) parts of the Rock Circuit Trail is the fairly short stretch from the reservoir to the Woodland Path intersection where you can take a right and be at the Flynn Rink in five minutes, just in case you need concessions or a bathroom break. If not, well, the easy stuff is done and now you need to get ready for what they call a “leg blaster” of a hike, doing nearly constant ups and downs for a good mile or so, and with some limited views here and there.

Things get pretty interesting toward the latter part of this stretch, as one more steady climb will bring you to an historic site that’s basically the foundation of the long-gone MIT Observatory. This site, which dates back to the 1800s, includes little more than a stone foundation and a bulletin board giving all kinds of information about the observatory, and even though there are no real views here, the sheer remoteness of the site and the fact that it is so difficult to find makes it a rather special spot that’s a good place for a break.

If you decide not to take a breather here, a break will surely be warranted a few minutes later upon reaching Boojum Rock, a rugged outcropping with some tremendous views of the Boston skyline. Once again, views of Boston Harbor and the communities below can be had, and on a clear day the Blue Hills to the south can be seen as well.

The Rock Circuit Trail can be very tough to follow from Boojum Rock, so it’s particularly important to always be watching for the white blazes on the trees and rocks from this point on. The trail drops down to the left through a narrow notch from Boojum, then zigs and zags with some more great views straight ahead and off to the right. It soon comes to a major intersection at which point you may look up and say “No way,” as a seemingly impossible climb awaits straight ahead.

This steep scramble takes you to the top of an unnamed hill with more views far below, then the trail starts a fairly long and steady drop until it reaches another section of the Fellsway East road which you’ll need to cross once again. From here, the Rock Circuit banks to the right and soon reaches a steep and rather menacing-looking rise called Pinnacle Rock.

Even if your legs are rubbery at this point, it is worth getting one more burst of energy to climb up to the top, as its steep and narrow cone affords what some consider the greatest views in the entire Fells, including an open view of the Boston skyline that has to be seen to be believed. From here, it’s a quick but grueling scamper up and down more rocks and boulders to the Cross Fells Trail intersection where you take a right and head back to Elliott Road.

The Middlesex Fells has countless trails and some truly great places to check out both on the east and west sides, but for a sheer “bang for the buck” experience, the short but oh-so-intense Rock Circuit Trail is tough to beat. And much like the Skyline Trail in the Blue Hills, it’s one that will get you in shape quickly for the more serious hikes far away from Boston while at the same time being only being a few miles away from the city.

Maps for the Rock Circuit Trail and the Middlesex Fells can be found at friendsofthefells.org.