FRESNO — The coolest place in Fresno?

If it’s summer, there is no contest.

It’s the Baldassare Forestiere Underground Gardens.

There are close to 10 acres of subterranean passageways, rooms, and courtyards.

And in the blistering heat of a summer day, it’s not only out of the sun but cooler by a significant number of degrees.

That said, it’s a cool and unusual attraction beyond being just a place to beat the heat.

There are hour-long guided walking tours of the underground gardens that made CNN.com’s list of the “World’s Coolest Underground Attractions.”

The cost is $25 for those between 18 and 59, $23 for those over 60, $14 for ages 5 to 17 while those 4 and under are free.

You can book tickets online at undergroundgardens.com.

So what’s the story of how the underground gardens came about?

Baldassare Forestiere was an immigrant from Sicily in 1901. His dream was to be a citrus farmer in the heart of the San Joaquin Valley.

It didn’t take long for him to run into roadblocks.

The hardpan soil of the land he bought was unsuitable for citrus trees.

The 100-degree plus temperatures in the summer didn’t help either.

Forestiere first dug a small cellar in 1906 in a bid to escape the summer heat.

He found it to be cooler below ground.

That prompted him to carve a series of attached rooms to effectively create an underground residence.

Forestiere then began experimenting with growing trees in underground chambers with skylights.

He found that with care they would grow well, and being below ground protected them from frost.

Forestiere — using hand tools and a pair of mules — continued expanding and improving these underground gardens until his death in 1946.

He fashioned a subterranean complex of patios, grottoes, and garden courts, all featuring arches and stonework using the local hardpan sedimentary rock.

He became a self-taught artist, and patterned his underground world after the ancient catacombs that is said he admired as a boy, near his home town of Filari, Sicily.

No plans were put on paper.

Each room and passageway was created in Forestiere’s mind as he worked. With simple farm tools such as a pick, a shovel, and a wheelbarrow he dug and carved the hardpan for 40 years when he wasn’t working earning a living growing and harvesting citrus.

Fruit-bearing trees and vines in the underground complex have grown up to 20 feet.

His trees included grapefruit, oranges, and lemons.

Other plantings included kumquat, loquat, jujube, carob, quince, and dates as well as wine and table grapes.

Fruit could easily be plucked from the surface of the gardens by simply bending down.

The plants and trees, some of which are over 100 years old, are protected from the frost in the winter months by virtue of construction.

Each level was planted at different times, so they bloom in succession, in order to lengthen the growing season. Trees and vines were also planted above the dwelling, acting as insulation and forming canopies that provide protection from the elements.

There are 65 rooms in the Forestiere Underground Gardens.

It has a summer bedroom, a winter bedroom, a bath, a functional kitchen, a fishpond, and a parlor with a fireplace.

You will also find grottoes and courtyards amid the stone walls and archways.

They allow for pockets of light.

The intricate pathways were created section by section, over a span of 10 acres.

There are three levels within the underground structure, one 10 feet, one 20 feet deep, and one 23 feet deep.

The gardens have skylights and catch basins for water.

The dirt that was moved to create the large structure was used elsewhere to fill planters, create stones placed within the catacombs, and to level out other parts of the land.

The hardpan he excavated was reused as bricks for archways and supports.

The pathways and rooms were constructed with various widths to help direct airflow by creating pressure as it moves through narrower portions and maintain movement as it bounces off the slants and curves of the cavernous walls. The conical skylights allow for the hot air to be pushed out more quickly and the cool air to remain below.

The gardens are operated by members of the Forestiere family through the Forestiere Historical Center, and can be considered an ‘unconventional example of vernacular architecture.’

The gardens were listed on the National Register of Historic Places in 1977 and registered as No. 916 on the list of California Historical Landmarks in 1978.

The underground gardens are located on Shaw Avenue in north Fresno a short distance from Highway 99.