According to MNN.com, "Today, the city of Pisa in Italy is undoubtedly best known for its Leaning Tower, but during the Middle Ages Pisa was a thriving seaport, home to Portus Pisanus, one of the most influential harbors of its time." Scientists recently discovered how harbor in Pisa has changed over the centuries. Researcher David Kaniewski led the study. His group took samples of sediment layers. <br />
