Philatelists will love this tiny museum with its letter boxes, mail coach and drawers of old postage stamps, including a rare Penny Black. Look for the beautiful stamps created in the early 20th century by Czech artists Josef Navrátil and Alfons Mucha. Across the street is the Petrská Waterworks Tower (Petrská vodárenská věž), which was built about 1660 on the site of earlier wooden ones. From here, wooden pipes once carried river water to buildings in Nové Město.
