I NEVER WENT to sleep-away camp, but I’ve always held a secondhand sense of nostalgia for the idea. As a kid, it was easy to tell which of my classmates were campers when school resumed each September. More outgoing after unlocking new levels of independence and bronzed from endless hours outdoors, they seemed to possess a stronger sense of self. I was so envious. So when a friend invited me to join her at “a luxurious summer camp for adults,” my younger self jumped at the opportunity. The destination? The iconic Mayflower Inn & Spa.

The historic hotel is located in Litchfield County, Connecticut’s idyllic countryside — a mere two-hour drive from New York City. Surrounded by 58 acres of lush gardens and woodlands, the inn makes a significant first impression. I park next to a McLaren, wondering if my companion meant to say “country club” instead of “summer camp.” But any fears of feeling like an outsider quickly subside as the concierge welcomes me by name, handing me a printed list of activities such as qigong (a practice of tai chi-style movements), croquet, and tarot-card reading.

“We’ll light the bonfire around five,” the concierge says, “and you can sip bourbon and roast marshmallows as the sun sets!”

“Adult summer camp it is,” I think, circling the experiences I’m most excited to try.

After settling into our cozy suite, decorated with floral prints, eclectic ceramics, and a canopy-covered king-sized bed, I make my way to the spa. Now part of the Auberge Resorts Collection, the Mayflower Inn was recently refurbished in celebration of its 100th anniversary. The renovation included a significant upgrade to the stand-alone spa house which, by way of Auberge’s stewardship, is now operated by The Well, a luxury health and wellness club.

The grandness of the 20,000-square-foot spa is truly breathtaking. It includes a traditional hammam, or Turkish bath, with aromatherapy and a biophilic thermal pool lined with hundreds of plants, which makes it easy to forget that I’m only a few hours from the city. After joining a pool ai chi class (think tai chi but underwater), I curl up on a lounge chair with a cup of rich, savory bone broth. Cell phones are prohibited in the relaxation rooms, a helpful prompt to gaze out the floor-to-ceiling windows facing a tranquil, tree-lined pond that mirrors the sky above. I look on as a father and son paddle by in a red canoe.

I join my companion for lunch where I learn that it was during a stay at the Mayflower that writer Amy Sherman-Palladino came up with the story for the hit TV show “Gilmore Girls.” Being New Yorkers starved for quality time in nature, my friend and I discuss the healing effects of our wholesome setting over poached trout and grilled halloumi cheese while sipping sparkling apple cider and strawberry shrub.

As I make my way back to the main building, past the tennis courts, chef’s garden, and poets maze, I encounter a “field and farm” mixology class, where guests make cocktails using ingredients from the surrounding countryside. I pause for a rest in a giant hammock under a tree because … well, I can’t remember the last time I spontaneously napped in a hammock. Back at the inn, I find my friend sitting by the fire. She has sweetly set up a pink-and-green acrylic checkerboard that was custom made, our server proudly informs us, by Edie Parker, a home decor brand, whose founder is a frequent guest of the resort.

Dinner is a five-course New England–style seasonal meal by Chef José Ramírez-Ruiz, the former co-owner and head chef of Michelin-starred Semilla, once located in Williamsburg, Brooklyn. The roasted branzino, served with fennel, sumac, and sunflower, is crispy and aromatic. But after an activity-filled day, we’re fading by dessert. Clairvoyantly, our server suggests we enjoy our last course upstairs in our suite. Giggling like children sneaking a midnight snack at a sleepover, we eat our rhubarb sorbet and chocolate mousse in our robes, taking turns reading aloud from the bedtime story left on our pillows during turndown service.

In the morning, my friend disappears for a lymphatic-drainage massage while I opt for intuitive yoga (a more exploratory and flowing practice than other forms that emphasize static postures held for a set number of breaths), followed by forest bathing — the Japanese practice of immersing yourself in nature. When we eventually reunite, there’s a sense of shared sorrow as we sit for our last meal at the inn, neither of us ready to return to our responsibilities back home. I wonder aloud how summer camps originated. After consulting her phone, my friend informs me that the very first summer camp was started right in Washington, Connecticut, where the Mayflower Inn is located today, and that they were born from a desire to connect city kids with nature. We leave, already plotting our return like campers counting down the days until we’ll meet here again.