Mammoth Cave National Park played host to 29 immigrants on Thursday from 12 countries.

They and their families descended stone stairs and walked the site’s winding caverns into darkness to a canyon room known as the “Methodist Church.” When they ascended, the sun shined bright on 29 newly naturalized American citizen.

The immigration process is long and complicated, demanding knowledge of laws, civics, English and more. U.S. District Court Magistrate Judge H. Brent Brennenstuhl congratulated each participant on their successful navigation.

“Ladies and gentlemen, having satisfied all the requirements under law and having just taken the oath of allegiance to the United States, it is my great personal honor to get to be the first person to welcome you and congratulate you as citizens of the United States,” Brennenstuhl told the crowd.

The most common nationality at Thursday’s ceremony hailed from the Democratic Republic of the Congo in central Africa, making up 11 of the 29 participants.

Many, like Iriza Kirenga, sought refuge in the U.S. from violence and government oppression. She escaped to Rwanda as a refugee before getting the chance to move to the U.S.

Kirenga has been in the U.S. for roughly five years, but on Thursday, she was a citizen for the first time. She said now she has “so many” opportunities before her.

Kirenga said she faced barriers and bias as she adjusted to life here, especially when learning English, and hopes to help others like her through nonprofit organizations now that she is a citizen.

She said she was “feeling free” after officially becoming an American.

Mammoth Cave Park Superintendent Barclay Trimble said ceremonies like this have been common at the park for years and are always “the highlights of my career.”

“For all the park staff that were here, we all just enjoy having this,” Trimble said. “And on top of that, during National Park Week, it even makes it a little more special.”

He said he hopes participants walked away thinking of “the new love for the country that they’ve now adopted as their new home,” made more special by celebrating at a World Heritage Site.

“There’s not many people during these naturalization ceremonies that are going to be able to say they did it 100 feet underground in a World Heritage Site,” he said. “Just having that as the backdrop for what’s already a very special experience for them for their special day, we’re just happy to be part of it.”