(1) Fonthill Abbey - a gothic folly built by William Beckford in 1796 in Wiltshire, England.

(2) A residence in Doylestown, PA built by Henry Chapman Mercer. "Fonthill Museum is a non-profit educational institution administered by The Bucks County Historical Society. Built by Henry Chapman Mercer, Fonthill served as his home and today is interpreted to reflect Mercer's ideas and concepts in the realms of architecture, museology, ceramic art and historical research." -- the Bucks County Historical Society, from the Mercer Museum web site.

Added 2000/09/18:
The book Fonthill : The Home of Henry Chapman Mercer--An American Architectural Treasure in Historic Bucks County, Pennsylvania by Thomas G. Poos has been re-issued (it was first published in 1985). Here are the specs: Paperback - 102 pages (September 15, 2000) Manor House Publishing Inc.; ISBN: 0964584425. I found it listed on several book sites.