You don't have to walk very far to encounter one of Philadelphia's more than 3,000 public murals. But the best way to see what's perhaps the most impressive collection of all is by hopping on the Market-Frankford line. A Love Letter to You, a series of 50 works on buildings in West Philadephia depicting the story of a guy wooing a girl, can mainly be seen from the elevated train line. The murals, which resemble old-fashioned ads, are both witty and touching, with messages like "We share defeats, we share receipts and we share the sheets" and "Miss you too much not to love you." You can download a guide for your own experience or join a Mural Arts Program tour held at 10 am on Saturday or 1 pm on Sunday.