BALTIMORE, MD - DATE - The walls and shelves of the reading room at Evergreen House are teak. On the lunette is a mural by Miguel Covarrubias depicting Amsterdam, one of John Work Garrett's diplomatic posts. (Photo by James F. Lee For the Washington Post) (James F. Lee/FTWP)

“We’ve been riding the grounds here since these guys were little,” said Baltimore resident Michael Maloney as his two boys swooped past us on their bicycles.

Today the family decided to take a closer look. “We peeked inside and saw the theater,” said his wife, Carolyn Maloney. “We are absolutely coming back. It was beautiful.”

They were talking about Evergreen Museum & Library, an Italianate mansion built in 1858 that sits on a wooded hillside in northern Baltimore. Like many Baltimoreans, the Maloneys, who live less than a mile away in the Homestead neighborhood, didn’t realize what was in their own back yard.

My wife, Carol, and I recently toured Evergreen, the former home of the Garretts, a local family that made its fortune in railroads. Turning off North Charles Street, we glimpsed the house through the trees, a pale yellow Gilded Age beauty crowned by an imposing white cornice and boasting massive white pillars in front (unfortunately marred at the moment by scaffolding). The place reminded me of a giant wedding cake.

In 1878, T. Harrison Garrett and his wife moved into Evergreen and transformed it from a summer rental for millionaires into an estate worthy of a wealthy family. They added rooms to accommodate their three children and to display their vast collections, gathered on travels around the world: Tiffany glass, Japanese inro (miniature cases) and German porcelain, as well as paintings and rare books and coins.

The Garretts’ eldest son and heir, John Work Garrett, shared his father’s passion for collecting and travel, which may explain his choice of career as a diplomat. While serving at the U.S. Embassy in Berlin, he met Alice Warder, an American studying voice there. They married in 1908. It was an ideal marriage: As they traveled Europe and South America to John’s various posts, Alice collected art pieces, often directly from the artists themselves. When John inherited Evergreen in 1920, they had the perfect place to display their treasures and began an ambitious program of enlarging the house to its current 48 rooms.

Our guide to Evergreen was Geordan Williams, a Johns Hopkins University history major from Arizona, who enthusiastically regaled us with stories about the Garretts during our 90-minute tour. John Work Garrett willed his estate to the university with the understanding that it would not become simply an art museum. Garrett wanted the house to appear the way it did when he lived there. Interspersed with paintings, sculptures and other artwork, tea trays appear ready for guests, a cigarette pack rests on a side table, a magazine lies open as if the Garretts would be back any minute. “You won’t see many glass cases in the house,” Williams said.

Alice Garrett is really the star of the house. About a dozen portraits of her, by artists such as the Spanish painter Ignacio Zuloaga and the Russian painter and stage designer Leon Bakst, are scattered throughout the house. An enormous Zuloaga painting of Alice in a Spanish dress dominates the drawing room. When Carol asked about the dark shadows under Alice’s eyes, Williams explained that she often dabbed coal dust there to give herself a Mediterranean look.

Today the drawing room is in a French salon style with Tiffany lamps, Ming porcelain and two large chandeliers. On the walls are a self-portrait by Picasso, a Degas drawing and an oil portrait by Modigliani. In earlier days, when Cole Porter entertained Alice and John and their friends at the grand piano, the room was in an Italian Renaissance style, with columns and an elaborate ironwork ceiling.

From the drawing room we made our way to the reading room, a charming teak-lined library with several archways leading into inviting reading nooks. Murals by Mexican artist Miguel Covarrubias, famous for his Vanity Fair cover art, adorn the tops of four of the arches and four wall panels, each depicting one of John Work Garrett’s foreign posts.

The cozy warmth of the reading room didn’t prepare us for the jaw-dropping elegance of the Great Library, a stunning room with floor-to-ceiling walnut bookshelves, reading areas and statuary. I half-expected to see Lord Grantham from “Downton Abbey” reading his newspaper there. It was the Garretts’ favorite room. On the day of our visit, sunlight streamed through tall arched windows, giving the walnut a golden hue. The treasures housed in this room alone are worth the visit to Evergreen: a complete Audubon double folio collection, the first Bible printed in North America, a Tang Dynasty camel statue and more than 160 incunabula, books printed before 1500.

Above the fireplace is a large Zuloaga portrait of Garrett fils, painted when he was ambassador to Italy. He is seated and dressed casually with an open collar and an informal jacket. Williams pointed out that Alice disliked this painting of her husband because “he was too underdressed for a man of his status.” But perhaps more interesting than the painting was a stain on the floor made by the water bowl of the Garretts’ beloved dog, Boston Baked Beans, who used to lounge in the sunlight near the back window.

Alice wasn’t content to display herself in paintings only; she needed a stage. In 1923, she converted the house gymnasium into a private theater, complete with a lobby, a stage and a curtain, where she would sing and dance for her guests. Her friend Leon Bakst stenciled the walls with Russian folk-inspired designs; Bakst even designed many of her performance costumes. Today, the theater is a site for public concerts.

The Garretts, father and son, collected many fine art objects from Japan, most of which are displayed in the Far East Room. Many of the items here are small: lacquered boxwood and ivory incense boxes, masks, inro and netsuke (miniature sculptures). Our favorite was a tiny piece of fruit with a carving of three men inside drinking tea.

Perhaps the most startling room is the Gold Bathroom on the second floor. Roman tile mosaics line the walls, floor and ceiling, while the bathtub and commode are covered in 23-carat gold leaf. “This is the only gold toilet seat in the United States,” Williams said. “And notice that there’s no toilet paper dispenser, but there is a call button.” Then he added, “That’s a joke I took from another tour guide.”

Just finishing a tour, Dick Hires of Chesapeake City, Md., a long-ago Johns Hopkins graduate, said that he used to drive past the house all the time during his student days. “I never knew what Evergreen House was,” he said.

Somebody else just found out what was in his back yard.

Lee teaches journalism at Bucknell University.