The Piazza di Sienna competition has been held annually in Villa Borghese park since 1922 (with a few years off for World Wars). The 67th CSIO will be a major shake-out and rehearsal for the Sydney Olympics. The second session of the Piazza di Sienna 2000, CSIO 68, will be held from 12-15 October. Concurrent with the May 25-28 session will be contests to determine the Italian junior championship.
A calendar of events has been posted on the Internet. Exact time slots will be filled in as the dates of the events approach and as actual arrival and fitness of competitors are determined -- it's always like that with internationals. Of special interest will be the famous precision horse drill, the Carosello dei Carabiniere which is scheduled a part of the last day's closing ceremonies.
Announcement of the Piazza di Sienna 2000: http://www.romapreview.com/pagine/vivere/siena.html
Schedule for May 25-28 session (Scroll down): http://www.fise.it/nuovo%20sito/so3.htm
Federazione Italiana Sport Equestri: http://www.fise.it/
Associazion Allevatori Cavalla Sella Sportivo Italiano: http://www.ciaoweb.net/acsi/
Mr. Horse World Equestrian site: http://www.mrhorse.it/