If you spend much time downtown, you may already know about this shady nook at (actually, below) the northeast corner of Congress & Scott. Or, if you don't visit downtown much, maybe — now that downtown is opening back up (after endless streetcar construction) — you'll want to come in to see all that's new in the past year or two... and take a break down under?
I spotted this park (but didn't go in because I didn't have my bicycle lock with me) July 28th.
Location: The park is west of the building at 97 East Congress, The Partnership: Pima County Teen Court. (Click there for a satellite view from Google Maps.)
Hours: Confusingly, one sign on the fence says "Park closed sunset to 7 AM." Another sign (not shown here) said "Park closed dusk to dawn." But I'd guess that the only time you can get in is when the building is open... so you can go downstairs, then head outdoors into the park. If you have more details, please leave a comment below or send me email.