 To maintain its base, the tower was transformed into a clock in the mid 19th century.This clock tower was one of the materials used by scientist Pierre Méchain as he measured the length of the meridian arc between Barcelona and Dunkirk in 1791, which led to the creation of the decimal metric system.La Llotja, another building found in La Barceloneta neighborhood, is a neoclassical building with a Gothic interior built in the 14th century.