CONCORD — As Route 2 crosses Interstate 95 heading west, it narrows, and so does the world around it. Leaving the city behind, it passes woodland, stone walls, a roadside stand with homemade pies. Bearing left at the sign for Concord, it eases up the hill to its most famous landmark: Walden Pond.

Ringed tight by woods of pitch pine and oak, the kettle-hole pond is a place of quiet majesty, a beloved retreat for swimmers, trail runners, and literary pilgrims. Kids swarm its shallows on summer days, and solitary figures cut through its deep waters at dawn. Visitors add rocks to the cairn of Henry David ­Thoreau, and ponder his call to live deliberately.

It is a place where history runs deep and the mind takes flight. And to those who speak of Walden with something approaching reverence, it has a mystical quality all its own.

“It’s a deeply spiritual place,” said Margrit Romang, an ­Arlington resident who comes to swim Walden’s mild, calm waters two to three mornings a week. “It helps you be mindful, to live in the moment. It helps you come back to yourself.”

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Romang bypasses the main beach for a quieter spot, down the footpath that circles the pond and leads to the hillside where Thoreau’s cabin once stood. There, a series of flat rocks descend like a staircase into the still water.

“No buildings, just trees and sky,” she said. “It’s very lovely. I love the way the light changes on the water.”

Walden draws a diverse mix of local residents and tourists through much of the year, but the number of visitors peaks in summer, when the park regularly reaches its capacity, ­defined by the state as 1,000 people. On Thursday morning, the main beach was bustling by 10 a.m., but the rest of the 62-acre pond remained nearly untouched. Just a smattering of swimmers made their way languidly through the water.

“It’s really pristine,” said ­Patsy Wood of California, here visiting family. “It’s as if you’re back in the 19th century.”

Wood, 62, grew up in ­Concord, but not at Walden. It was not cared for nearly as well back then, she said. But now she comes to the state-run park every day of every visit.

Up the hill behind her, a group of runners glided along. With its vast network of trails, the pond draws runners from across the area, its cooling ­waters a perfect way to wash away the miles. They ran past a beach where a few kayakers pushed off.

At the main beach, solitude gave way to commotion. Young parents watched their clamoring children from shore and tried to make their way through a page, maybe two, of their books. Teenagers caught some sun while tapping away on their phones, tourists clicked pictures, and retirees sat back and took it all in.

One swimmer ended a lengthy session in the water, then quickly changed into running gear. She was training for a triathlon, she said before bounding off. No time to chat.

Wood and others said they thought Thoreau would be pleased by the crowds, even if the chorus of children’s squeals did not lend itself to deep contemplation. A place this beautiful deserved to be ­enjoyed, they agreed.

“I think he’d be thrilled,” Wood said.

As the morning progressed, more and more people arrived. Most were there for the beach and a dip on a humid day. But a few made their way down the path to see where Thoreau once lived and to read his famous words.

“I went to the woods because I wished to live deliberately, to front only the essential facts of life,” a sign read. “And see if I could not learn what it had to teach, and not, when I came to die, discover that I had not lived.”

But many knew little of the transcendentalist writer, except that he had chosen a fine place to call home. Carlos Salinas, an East Boston resident visiting Walden for the first time, said a friend had told him how nice it was, and he came with his two children to see for himself.

“I have never seen such a beautiful pond,” he said. “The water is so clear.”

On his day off from work at a candy factory in Revere, Salinas surveyed the pond from a picnic table in the shade. Even with the bustle by the beach, it was a restful place, he said.

On a quieter beach off the footpath, Sarah Greenberg lay in the sun. It was only a month ago that she started coming here from her home in Jamaica Plain. But now she was coming three times a week for a morning swim.

“It’s like a meditation,” said Greenberg, who works at Salem State University. “It makes the whole day feel different.”

At the end of the pond, near Thoreau’s cairn, a woman dried off from her swim. She said she is not much of a swimmer, and does not venture far, just far enough that the essentials, the water, the treeline, and the sky, take hold. Just the movement of the water, and the sound of her breath.