Baltimore's Phoenix Shot Tower, also known as "the Old Baltimore Shot Tower," was the tallest structure in the United States when it was built in 1828. Its cornerstone was laid by Charles Carroll, the last living founding father and the richest man in America at the time.
Shot towers were the most common method of producing shot balls for muskets from the late 18th century to the 1960s. From the very top of the tower workers would pour molten lead through a sieve. While falling through the empty tower, the lead would cool and form into perfectly round balls. These would land in a basin of water to be cooled further.
The Phoenix Shot Tower's average annual production was about 10,000 bags of shot a year, much more during wartime. In 1921 it was purchased and plans were set in motion to replace it with a gas station, but the citizens of Baltimore strongly objected. By 1928 the city had bought the tower back and it became one of Baltimore's first National Historic Landmarks.