Rowena Cade financed & designed the Minack Theatre in the cliffs of Cornwall. When she was 38, she and two craftsmen built the first stage and seats. She developed techniques for wet cement work, inscribing lettering and Celtic motifs. She fetched sand up the steep way from the beach, and carried huge beams. She looked frail, but she worked in all sorts of weather until she was in her mid-eighties; just before her death at 89 she was still sketching ideas for improvements. More at link.