If you like nothing better than to imagine how the other half lives, you'll suffer no shortage of old homes to sigh over in Boston's Back Bay. Most, unfortunately, are off-limits to visitors, but there's no law against gawking from the outside. Stroll Commonwealth, Beacon, and Marlborough streets for the best views. For details on lectures, films, and other events offered in some of these respected institutions, see the free, biweekly Improper Bostonian and the Boston
Globe's "g" section.