As the Marconi Conference Center prepares for a major facelift, its new operators are planning an open house on the day set aside each year to celebrate its namesake. On April 22—International Marconi Day—the new operators of the Marshall site will host the first of what will become an annual open house at the Marconi State Historic Park, where the conference center is located amid a network of hiking trails overlooking Tomales Bay. A week later, renovations will begin on 45 rooms in buildings located around the 62-acre site. The work is expected to be completed in September. California State Parks owns the property but hasn’t had enough funding to maintain it, nor has the Marconi Conference Center Operating Corporation, the nonprofit that operates it. The funding situation became more difficult during the Covid lockdown. With the 15 buildings in disrepair, the M.C.C.O.C. began searching for a sub-operator with deep enough pockets to upgrade the center, which is home to a century-old hotel and cottages built by Guglielmo Marconi, the inventor of radio, to house employees of his transpacific receiving station. Last year, the M.C.C.O.C. signed a 55-year deal with Marconi Hospitality, a local branch of Nashville-based Oliver Hospitality, which has renovated several historic hotels in Tennessee and Georgia and the Station House Inn in South Lake Tahoe. Marconi Hospitality plans to rebrand the center, which is listed on the National Register of Historic Places, as an upscale coastal retreat: the Lodge at Marconi. The upcoming renovations do not include the center’s century-old hotel, which has been closed for over 50 years. “We’re raising money to refurbish the historic hotel over a longer period of time,” said Rodney Fong, a member of the investment team and a fourth-generation San Franciscan who attended high school in Marin County. “We’re not making any structural changes to the property,” Mr. Fong said. “We want to honor the coastal and cultural history of the place. When you get up there, you get a real sense of tranquility.” Marconi Hospitality wants to continue serving the nonprofit organizations, government associations and other groups that have frequented the center in the past, Mr. Fong said. But it also hopes to broaden its reach to private companies and guests seeking an upscale, spa-like experience. “The California coast is a worldwide destination that is enjoyed by both international travelers as well as people in our own backyard,” Mr. Fong said. “The location is world-renowned.” The American Marconi Company, which operated the transoceanic radio station, sold the property to the Radio Corporation of America in 1920, and the station was decommissioned 20 years later. The Synanon Foundation, a drug rehabilitation group that engaged in criminal activities, counted the site among its West Marin properties for years. In 1980, the San Francisco Foundation purchased the property from Synanon. The foundation owned the land for about a decade before donating it to California State Parks on the condition that it be used as a conference center and kept open to the public. “As a neighbor to the park, I’m extremely excited that somebody’s going to put some money into it and fix it up and make a nice place for people to come visit,” said Ken Dunaj, a neighbor and one of several West Marin residents who sit on the M.C.C.O.C. board. “International Marconi Day seemed like a really good time to have an open house and let the local community come see what we’re going to have here.” The event will feature live music, games for kids and a farmers market with food from local producers from 11 a.m. until 2 p.m. on Saturday, April 22.