A lot of American naturalization ceremonies take place in courthouses, and a few take place in national parks. But this Friday is believed to be the first time such a ceremony ever took place inside a cave in Mammoth Cave National Park.

Park officials say nearly 40 imigrants from 19 countries are expected to be on hand Friday during the ceremony, which will be presided over by U.S. Magistrate Judge E. Robert Goebel.

Mammoth Cave National Park Superintendent Patrick H. Reed and United States Citizenship and Immigration Services Louisville Field-Office-Director Geoff Verderosa will address the new citizens, and USCIS Immigration Services Officer, Mark Cox will present the candidates for naturalization to the court. Although this is the first time USCIS has held a ceremony at Mammoth Cave National Park, the agency routinely hosts naturalization ceremonies at other national parks across the country, according to a USCIS release.

Mammoth Cave National Park was established to preserve the cave system, including Mammoth Cave, the scenic river valleys of the Green and Nolin Rivers, and a section of hilly country typical of south central Kentucky. This is the longest recorded cave system in the world, with more than 390 miles explored and mapped.  Mammoth Cave National Park was designated as a World Heritage Site in 1981, and as the core area of as International Biosphere Reserve in 1990.