Baltimoreons seem to have a self-esteem problem, especially when it comes to culture. If it's good, they figure, it's not in Baltimore. If it's in Baltimore, it couldn't be very good. They drive in droves to Washington, DC to see the museums and don't even seem to be aware that the Walters Art Museum, one of the finest in the nation, is right on their doorstep.
If you haven't been, then just go. The Walters' collections cover everything from ancient art through the 19th century, with particular strengths in medieval and oriental art. They regularly bring in special exhibits that just knock your socks off. The museum is small enough to be enjoyed without sensory overload but large enough to let you really enjoy all areas of art history. Education and interpretation are also excellent--recorded tours are available, but you can also just read the signage and take it all in at your own pace. Then before you go, stop by their gift shop to get some unique gifts that you won't be able to find anywhere else in Baltimore.
Adult admission is reasonable ($10) and is free on first Thursdays and on Saturdays between 10 and 1. If you like it, get a membership--free admission all year, priority tickets for special events, discounts on lectures and courses, and a shop discount.