Unlike standard HVAC systems, small-duct systems save space, decrease humidity, are energy efficient, and can even be painted over to match a home’s interiors. That's why Unico—maker of The Unico System small-duct central heating and cooling solution, and a corporate partner of the National Trust since 2002—advocates for modernizing notable landmarks while preserving historic integrity.

Check out this list of 14 cool (literally) historic places around the U.S., many of which are open to the public.

President Lincoln’s Cottage—Washington, D.C.

Restored in 2008 through a capital project by the National Trust, this historic site and museum is the only place where visitors can experience the history of President Lincoln’s public and private life. A conventional HVAC system would have required removing portions of the cottage’s historic ceilings, walls, and floors to run new ductwork, so the National Trust recommended The Unico System.

The Petersen House—Washington, D.C.

The Peterson House, located across the street from Ford’s Theatre, was the setting for one of the saddest days in American history when President Lincoln succumbed here to the shot delivered by assassin John Wilkes Booth. The National Park Service, which maintains the house as a museum, chose The Unico System because its tubing can snake through small areas with minimal intrusion to its walls, floors, and ceilings.

Happy Days Lodge—Peninsula, Ohio

Built by the Civilian Conservation Corps (CCC) in the 1930s in Cuyahoga Valley National Park, this site derives its name from Franklin D. Roosevelt’s popular campaign theme song. The former president’s New Deal program included the CCC as part of its Depression-era job-creation efforts. The open “parkitechture” style of the site’s structure was impossible to cool with conventional HVAC systems; only The Unico System could provide guests with air-conditioned comfort without disrupting the lodge’s historic look.

Eichler Homes—San Francisco, California

Developer Joseph Eichler popularized the style of home that would come to be known as "California Modern" during the mid-20th century. These flat-roofed, post-and-beam construction houses are known for their open room designs, floor-to-ceiling windows, glass transoms, atria, and walkout patios—features virtually impossible for conventional HVAC systems to overcome, but a natural fit for The Unico System. Tours of these homes, located within enclaves throughout the San Francisco Bay and Greater Los Angeles areas, are organized throughout the year by the Eichler Network.

President Truman’s “Little White House”—Key West, Florida

President Harry S. Truman made this home—originally built in 1890 as a Naval officer’s residence—famous when he chose it as his winter vacation location and christened it the “Little White House.” Traditional HVAC would have required additional condensing units to achieve zoned cooling, whereas The Unico System allows individual chillers to work in a single area without the entire system running at full capacity.

Ernest Hemingway Home & Museum—Key West, Florida

Known for its six-toed cats and the first in-ground pool in Florida, the prolific writer’s home is meticulously maintained and receives thousands of visitors per year. However, the museum also began gaining an unwanted reputation when visitors often fainted due the stifling Key West humidity. Curators selected The Unico System to provide low-humidity cooling to the public without altering the property’s unique decor and architecture.

Hempstead House (Guggenheim Estate)—Sands Point, New York

The Hempstead House is one of four opulent, F. Scott Fitzgerald-era Gold Coast mansions on the grounds of the Guggenheim Estate. Built in 1912, this 50,000-square-foot Tudor served as the Guggenheim summer residence, where the family hosted lavish parties for the powerful elite of the day. The Unico System’s supply tubing snakes through existing ceiling cavities, and its mechanical systems are housed in servants’ quarters not used since World War II.

Rodman Candleworks—New Bedford, Massachusetts

In the mid-19th century, New Bedford supplanted Nantucket as the whaling capital of the world—for a time becoming America's richest city, due to the extensive use of whale oil throughout the country. Built in 1815, this building was dedicated to the production of candles from the ubiquitous oil. It was converted into a bank branch in 2017, and the project's restoration architect realized that only The Unico System would allow for modern comfort will preserving the structure's historic callback to New Bedford's seafaring heyday. The design was acknowledged with a preservation award from the Waterfront Area Historic League (WHALE), which organizes tours and events in historic New Bedford.

Chesapeake & Ohio Canal National Park Visitor’s Center—Washington, D.C.

Stretching from the tidal basin in DC to the mountains of western Maryland, the C&O Canal provided work for the people of the Potomac River Valley in the 19^th and 20^th centuries. Today, the visitor center in Georgetown is one of the popular destinations along the canal. The National Park Service chose The Unico System as part of the restoration for the two-story, 150-plus-year-old visitor center.

Mary Baker Eddy House—Lynn, Massachusetts

In this Massachusetts home, Mary Baker Eddy founded the Christian Science faith in 1875. The home underwent a complete restoration from 2011 to 2013, to return the structure to its historic 18th-century charm. The preservation architect working on the project chose The Unico System as the best method to include modern heating and cooling, without impacting the home's original aesthetics. Longyear Museum is dedicated to preserving the history of Mrs. Eddy and organizes educational tours of this home-turned-museum.

International Headquarters of the Order of the Eastern Star (Perry Belmont House)—Washington, D.C.

Washington, D.C.’s Dupont Circle neighborhood boasts many homes listed on the National Register of Historic Places, but few demonstrate the elegance and grandeur of a bygone age as well as this block-long Beaux-Arts mansion on New Hampshire Avenue NW. Originally called the Perry Belmont House, the wedge-shaped structure was built in 1909 for the eponymous U.S. congressman and Ambassador to Spain.The home was designed by famed French architect Ernest Sanson, who incorporated luxurious elements like elaborate ironwork from France, hardwoods from Germany, and marble from Italy, which evoke the opulence of the waning Gilded Age. In 1935, the building became headquarters for the Order of the Eastern Star, a Masonic branch.The 55,000-square-foot mansion was recently outfitted with The Unico System small-duct central air solution, which seamlessly incorporates modern indoor comfort to its splendor.

Monson Arts Center & Artists’ Colony—Monson, Maine

Located in the heart of the state, the tiny hamlet of Monson, Maine, suffered the fate of many American small towns when its largest employer closed during the financial crisis of the late 2000s. In 2017, a resurrection came in the form of a grant from the Libra Foundation, a philanthropic organization dedicated to spurring cultural and economic growth throughout the Pine Tree State. The restoration of many downtown structures, including the pictured general store, are part of a larger effort that has transformed the bucolic town into a full-blown artists’ colony, hosting international exhibitions and residencies. The Unico System was proud to play a part in the preservation of these historic buildings.

The Gable Mansion—Woodland, California

This gorgeous Italianate Victorian mansion in Woodland, California, was built for pioneer and rancher brothers Amos and Harvey Gable in 1885.The lavish home includes a central "stair hall" that has a curved stairway visible from the front entrance and several detailed, second-story bedrooms.The Gable Mansion has been lovingly restored over the years, including the addition of seven Unico Systems in the early 2000s.Though it’s a private residence currently for sale (if you have a spare $3-4 million, you can see its listing), its ornate gardens, landscaping, and stately exterior can be viewed during a drive down Woodland’s First Street.