This one will get a bit complicated--
XYSTUS. An AMBULATORY. In Greek architecture, a long portico used for athletic contests; in Roman architecture, a long covered or open walk bordered by colonnades or trees.
It's also the only X-word in my Penguin Dictionary of Architecture, Third Edition! Anyway, now we have to look up...AMBULATORY. A semicircular or polygonal aisle enclosing an APSE or a straight-ended sanctuary; originally used for processional purposes.
And finally, we turn a couple of pages and find:APSE. A vaulted semicircular or polygonal termination, usually to a chancel or chapel.
Whew. So, to start off with, for all you xystus fans, here's one you'll like from an 18th Century engraving, demonstrating its application to the garden. And from a very comprehensive site associated with the University of Pittsburgh, some diagrams by Jane Vadnal of an ambulatory, and of an apse. Posted by Terry Oglesby at December 22, 2005 10:51 AM