FRESNO, Calif. -- It took Baldassare Forestiere nearly 40 years to carve the underground gardens in Fresno, Calif., that bear his name.

Silvio Manno didn't take quite as long to publish the first historical book about the gardens -- but there were moments when it felt like it.

''The Forestiere Underground Gardens: A Pictorial Journey'' (Ionian Publications, $29.99) is a new room-by-room tour through one of the most unusual constructions in California, if not the country. The gardens essentially were a one-man creation that Forestiere began as shelter and continued as artistic impulse. They wound up being his legacy.

Bill Secrest Jr., a local historian, believes the site is one of the nation's greatest examples of folk art.

''Forestiere created the gardens out of what was already indigenous to the landscape,'' he says. ''It's unique. It's a whole habitation constructed out of somebody's sweat equity. How many houses in America can you say were constructed similarly?''

Using little more than a shovel, pick, wheelbarrow and his imagination, Forestiere carved his living quarters in about eight years, starting in 1906. He continued to dig, expanding the grounds by 1923 to 10 acres of patios, walkways and chambers.

About a third of the labyrinth was destroyed during construction of Highway 99 and other nearby building in the mid-20th century. But what was left remains much as it did when Forestiere died in 1946.

''You're amazed that it's as big as it is,'' Secrest says. ''One person working solitary for 40 years was able to create that. It's an astounding construction, even if a team of people had done it.''

Nearly as impressive, he says, is Manno's book, which began to take shape more than 10 years ago.

Manno, an Italian immigrant and amateur photographer, started aiming his lens in 1994 at the textured surfaces and delicate sunlight that trickles through the cavernous excavation.

He first visited the gardens during the late 1970s, a couple of years after moving to Fresno, Calif.

''It was reassuring and very soothing, because it was a very familiar style of architecture,'' says Manno, 51. ''It reminded me of the primitive dwellings where I actually was born and spent the first six, seven years of my life, in Calabria.''