GREAT question! I've been living here almost 3 years and visiting for the previous 10 years and never seen it for myself. I've even seen Rick Steves and numerous other travel experts talk about it but there it remains a constant mystery to me.
If you go to Google Maps at
http://www.Google.com/maps and write the following in the search bar (exactly), you'll find it (not mapped on "Street View", however):
Monasterio Del Corpus Christi, Madrid, Spain
And now that I see it on the map I know exactly where it is. I've walked past it dozens of times too, but didn't realize THIS was the place where you buy sweets and biscuits via the "mystery wheel".
Saludos, MadridMan
_________________________
Visit BarcelonaMan.com for Barcelona information, Transportation, Lodging, & much MUCH more!
Curious about what could POSSIBLY be inside the brain of MadridMan? Visit
MadridMan's Madrid Blog