What’s beneath your feet probably isn’t the first thing you think about when visiting a historic site. However, many of the nation’s historic homes and other structures sit atop unique subterranean infrastructure. Some of these hidden spaces are accessible to visitors and just as exciting as what’s above ground — from tunnels turned art galleries to an old bootlegger’s den. Whether you’re looking for a spooky site to visit during Halloween season or a place to cool off during the summer months, here are four basements to see at National Trust historic sites.

Kykuit (Tarrytown, New York)

This classical revival-style mansion was home to four generations of the Rockefeller family, beginning with businessman and philanthropist John D. Rockefeller, who lived in the house following its completion in 1913. Today, visitors to Kykuit will find lush gardens, historic designer interiors, and fine furnishings. Tucked into the home’s long, tunnel-like basements, visitors will also find “an impressive collection of modern art that can be seen just as it was installed while Nelson A. Rockefeller and his family lived there,” according to Katrina London, curator at Kykuit. John D. Rockefeller’s grandson, Nelson A. Rockefeller, who served as four-time governor of New York and vice president under President Gerald Ford, converted the tunnels into a gallery space for his growing modern art collection in the 1960s.

Another highlight of the mansion’s underground collection is a series of a dozen tapestries by French textile artist Jacqueline de la Baume Dürrbach. London said it is “a unique collection… depict[ing] some of Pablo Picasso’s most notable paintings from over fifty years of his career.” De la Baume Dürrbach is best known for having co-created the tapestry of Picasso’s Guernica, which has hung at the United Nations in New York City since 1985.

Distinctive ceiling tiles also mark Kykuit’s basements. Arranged in a herringbone pattern and less than one inch thick, the revolutionary terracotta tile arch system was patented in the United States by Spanish engineer Rafael Guastavino.

Now home to an impressive art collection, the tunnels were initially designed to support garden terraces designed by Beaux-Arts architect William Welles Bosworth. The tunnels also provided a play area for the Rockefeller children during bad weather, and paths for servants to traverse the estate underground and access to the subterranean machinery for some of the site's 24 recirculating fountains.

Kykuit’s basements are accessible to visitors on public tours offered by Historic Hudson Valley from May through November.

Lyndhurst Mansion (Tarrytown, New York)

Lyndhurst Mansion is one of the nation’s finest examples of Gothic Revival architecture. It has housed a series of notable occupants since architect Alexander Jackson Davis designed it in 1838, including New York City mayor William Paulding, merchant George Merritt, and railroad tycoon Jay Gould. Today, visitors to the mansion can enjoy a vast collection of art, antiques, and fine furniture.

Perhaps no space at Lyndhurst Mansion is more inviting to visitors during the hot summer months than its beehive-domed root cellar. The cellar was added to the home during an expansion in the 1860s as a place to store food and other perishable items. Underground, the Earth’s natural cooling barrier helped keep things cool and fresh without refrigeration. To assist in cooling, ice blocks from the mansion’s ice room, where the blocks were stored in sawdust, were brought into the root cellar during the summer months. A drain in the cellar floor kept water from puddling. The cellar’s roof is built from brick in the shape of a dome, modeled after the shape of cultivated straw beehives. The center of the roof has a metal cover with specks of glass to allow in natural light. Today’s electrical lighting was added after the 1860s expansion.

Lyndhurst Mansion’s root cellar is accessible to visitors on their "Backstairs" or "Upstairs-Downstairs" Tours, which look closely at the life of the service staff and the spaces where they lived and worked.

Woodrow Wilson House (Washington, D.C.)

Villa Finale, San Antonio, Texas

It is unusual for homes in Texas to have basements. But at Villa Finale, an Italianate mansion in the King William Historic District of San Antonio, Texas, the small basement and unconnected wine cellar are only half as strange as some of the historic figures who once called the mansion home. Built in 1876, Villa Finale housed a series of eccentric owners before preservationist Walter Mathis bequeathed it and his eclectic historical collections to the National Trust for Historic Preservation in 2004.

Mathis called Villa Finale’s basement “The Tavern” and used it as a game room. An extensive collection of early Texas pieces is still housed in the basement, including a poker table from San Antonio’s Casino Club on Market Street, the city’s first social club and theater. Also exhibited in the basement are several German beer steins, English Ironstone table pieces, and stoneware pieces and figurines. Because basements in older homes served as kitchens for heavier cooking, Villa Finale’s basement collection also includes many cooking-related articles, such as cast-iron utensils and bread and butter molds from early Texas. There are also family-related objects on display in Villa Finale’s basement, such as a chair that Mathis’s grandfather made from deer antlers.

“Visitors are always surprised at how small the basement is,” admitted Sylvia Gonzalez-Pizana, deputy director and curator at Villa Finale. But after the surprise wears off, they “marvel at how cool the room feels even without air conditioning—the perfect gathering place for a game of poker and an ice-cold beer!”