The joke here, of course, is that you can visit the art institute — Mia, as it asks to be called now — free of charge, provided you don’t insist on seeing one of its special exhibits. Mia only asks for “donations,” meaning penny-pinchers can sneak in and enjoy three stories’ worth of art without spending a dime. But that’s no way to live. Not when funding for the arts is on the chopping block in Washington, D.C., and philanthropists are compelled to send checks to the ACLU and Planned Parenthood, instead of the usual targets, like museums. Anyone who can afford it should visit Mia a few times a year, and drop them (at least) a $5 bill for the privilege of seeing centuries of art, of all kinds, all collected and staged in one magnificent place.