Ravensburg is home to a remarkable collection of well-preserved medieval towers and city gates. Highlights include the Grüner Turm (Green Tower), so called for its green tiles, many of which are 14th-century originals. Another stout defense tower is the massive Obertor (Upper Tower), the oldest gate in the city walls. The curiously named Mehlsack (Flour Sack) tower—so called because of its rounded shape and whitewash exterior—stands 170 feet high and sits upon the highest point of the city. From April to October, visitors can climb to the top of the Mehlsack or the equally tall Blaserturm (Trumpeter's Tower) for rooftop views over the city.