With so many glass condos going up in New York these days, it’s easy to become numb to the original surprise and beauty of modern architecture. Fortunately, now there’s a remedy: Beginning next week, for $25 plus a train ticket to New Canaan, Conn., New Yorkers can tour Philip Johnson’s Glass House. It is arguably the most iconic residential glass structure ever built, lodged in the most perfect setting imaginable: a gently rolling, lightly wooded 47-acre property that includes eight other Johnson-designed structures.

Johnson donated the property to the National Trust for Historic Preservation in 1986 with a life estate. After Johnson died in 2005 at 98 — and his partner, David Whitney, though three decades younger, followed him a few months later — the trust began preparing to open the property to the public. Ten-person tours, which require reservations, begin Monday; the official opening is June 23. The house will be closed between November and April each year for maintenance.

The National Trust completed some 26 preservation projects on the site, including replacing the Glass House’s roof, the executive director of the Glass House, Christy MacLear, said. Other projects pending in the coming years include developing the drainage systems and — a daunting challenge — replacing the Glass House’s glass walls.

Johnson left the house with an endowment of $8 million; an auction of Whitney’s art collection raised an additional $13 million. A board has not yet been formed, but Ms. MacLear has enlisted a roster of powerful collectors and philanthropists, including Agnes Gund, Aby and Samantha Rosen, and Peter Brant and Stephanie Seymour, to be on the invitation committee for the inaugural gala picnic.

The Glass House is one of only two modern houses owned by the National Trust, the other being the Farnsworth House in Plano, Ill., designed by Johnson’s mentor, Mies van der Rohe. Ms. MacLear, who has an MBA from Wharton and started a contemporary art gallery in Chicago, said her goal was to create a visitor experience that is dynamic, not scripted. “We didn’t want to create the classic house museum model — which I would characterize as ‘recreating the lives of…’ — because it would be so counter to the way the site operated during [Johnson and Whitney’s] lifetimes, which was always looking forward.”

To that end, the guides have been put through rigorous training, but encouraged not to talk too much, in order to let visitors take in the site on their own and ask questions. To cover the basic facts, each visitor will receive an artfully designed stack of cards, with photographs on the front and information on the back.

The Glass House has also launched a preservation initiative, of which the first phase will be a survey of more than 90 modern homes in New Canaan, conducted under an advisory board of eminent experts. The need for such an effort in New Canaan is urgent, one member of the advisory board, the dean of the Yale University School of Architecture, Robert A.M. Stern, said. “New Canaan is a victim of the same quote-unquote McMansion-itis that afflicts many suburban areas, so these houses, which often sit on beautiful properties, are threatened,” he said. “They should be valued as works of art.”

Johnson was one of the so-called Harvard Five architects — which also included Marcel Breuer, Landis Gores, John Johansen, and Eliot Noyes — who came to New Canaan in the late 1940s and made the town an unlikely center of modernism.

He bought the original five acres in 1947. The first structures, the Glass House and the Brick House, were completed in 1949. The Brick House, which served as a guesthouse, is like the yang to the Glass House’s yin: solid brick, with only three windows on the back. Through the years, Johnson purchased adjoining property and added structures: the pool in 1955, the Lake Pavilion in 1962, the underground Painting Gallery in 1965, the Sculpture Gallery in 1970, the Library/Study and the entrance gate in 1980, the Ghost House in 1984, the Lincoln Kirstein Tower in 1985, and the last building, Da Monsta, which was Johnson’s tribute to deconstructivist architecture, in 1995.

Johnson referred to the site as his “50-year diary.” “He had no allegiance to any ideology or any style,” the architect Peter Eisenman said in an interview. “He was a gadfly in that sense.”

Although many people at the time found it shocking, today the Glass House seems uniquely beautiful and calming. It is an elegant rectangle, with an open interior separated into “rooms” — kitchen, dining, living, bedroom — by arrangements of furniture. (Only the bathroom, situated in a brick cylinder, is enclosed.)

The house sits on a promontory, overlooking the landscape, and, with its setting, gracefully embraces a series of opposites: the manmade and the natural, interior and exterior, solid object and weightless air. “It’s an object in the landscape, like a Greek temple, but it has such great transparency that it’s like a breeze in the air. You hardly see it,” the architect David Childs said.

The landscape in a sense becomes the walls of the house, and it, too, was carefully sculpted. In the sitting area, juxtaposed with the Barcelona chairs and daybed, is a painting attributed to the French painter Nicolas Poussin — an allusion to Johnson’s interest in the 18th century idea of a pastoral Arcadia.

“It’s a reference to the idea of idealized landscape,” the Philip Johnson scholar Hilary Lewis explained. On the property, which was heavily wooded, Johnson removed trees to create a better view and a sense of depth, Ms. Lewis said. With those that remained, he trimmed their lower branches to create an elegant canopy.

The tour will include the Painting Gallery and the Sculpture Gallery. Through the years, Johnson gave hundreds of pieces to the Museum of Modern Art, but a small collection remains, including a substantial group of paintings by Frank Stella, a Warhol portrait of Johnson, and sculptures by artists including Michael Heizer, John Chamberlain, Bruce Nauman, and Robert Morris.

Because of the neighbors’ concerns about traffic, the visitors center had to be situated in town, across the street from the train station. Visitors will pick up their tickets there and take a small van to the site.

What was initially an inconvenience now seems like a blessing, an architecture critic and New School professor, Paul Goldberger, who is on the board of trustees of the trust, said. “Nothing would be worse than having to put a parking lot there.”