The organ is located in the S. Brunone Chapel, the northern extension of the S. Maria's main hall. It is a free standing instrument almost ten meters wide and 25 meters high with a hand-carved cherry wood case and a walnut and chestnut frame -- brittle woods for added resonance. The case holds four manuals and one pedal keyboard as well as 5,400 hand made tin pipes (77 stops), which give the organ a range that goes from double piccolo to triple basso. It is certainly one of the largest organs in the world.
The public debut of the Formentelli organ is scheduled to be in a pre-millennium concert sponsored by the Associazione Romana Arte Musica (ARAMUS) at 9 PM on December 30 (Bruckner: Locus Iste, Ave Maria, and Te Deum). But as noted above, the crew is tuning and testing the instrument, and there are occasional impromptu concerti almost every morning.
For a site map and pictures of the Baths of Diocletian and S. Maria degli Angeli e Martiri, go to:
http://www.b-ware.com/hive/fplans/baths.htm,
http://www.siba.fi/~kkoskim/rooma/pages/TDIOCLET.HTM, and
http://wings.buffalo.edu/AandL/Maecenas/rome/baths_diocletian/section_contents.html.
S. Maria degli Angeli e Martiri is also the location of one of the world's most famous sundials (yes, it is possible for sundials to be famous.) For information go to:
http://www.geocities.com/Athens/Aegean/2001/page10E.htm and, for links to more than any sane person wants to know about sundials, try