The oldest botanical garden in the United States and the former homestead of famed botanist John Bartram now serves as an outdoor classroom and living laboratory. The Common Flower Garden offers an unforgettable view of the city skyline. Gardens: free. Daily, dawn to dusk. Tours (in season): $10-$12. House only, Th-Su noon and 2 pm. Garden only, Th-Su 1 pm and 3 pm.