Here's our local dome. It and the entire building is made entirely of bricks and mortar...a freestanding elliptical dome with a span of 58 feet by 82 feet. Rafael Gustavino, the architect, worked on the Biltmore house as well, here in Asheville.
Wikipedia says this about the dome of the Basilica of St. Lawrence -
The basilica was designed and built in 1905 by Spanish architect Rafael Guastavino along with his fellow architect R. S. Smith and the surrounding Catholic community of Asheville, North Carolina. The Basilica is on the National Register of Historic Places and was elevated in status to a Minor Basilica in 1993 by Pope John Paul II. The basilica is the only basilica in Western North Carolina. The basilica's dome has a span of 58 by 82 feet (18 by 25 m) and is reputed to be the largest freestanding elliptical dome in North AmericaA publication by the Basilica gives more information HERE.
Tours are available, and I have already enjoyed one. Photos are allowed while walking through the building also.