Pisa’s origins remain uncertain: some theories say the city is of Greek origin, however the city was most probably founded by the Ligurians or Etruscans. During the Roman Empire Pisa became a privileged center due to the excellent disembarkation possibilities offered by its port. Following the end of the Roman Empire, Pisa remained a port city of great importance for the Goths, Longobards and the Carolingi. During the medieval period, Pisa reached maximum prosperity; the Marine Republic became one of the most important naval powers of the Mediterranean and extended its power over the entire coasts of Tuscany, Sardinia and Corsica. The amazing buildings in Piazza dei Miracoli were built around this period of great economic, political and cultural power and have made Pisa famous around the world. What actually marked the end for Pisa as a naval power was the unrelenting filling in of the port, due to the accumulation of detritus transported from the Arno. The city, surrounded by unhealthy swampland, lost its importance and its population until the 19th century, when the Grand Dukes of Lorena began the indispensable reclamation works. In 1810, Napoleon founded the Scuola Normale Superiore in Pisa, which to this day continues to be renowned as a school of excellence in Italy and abroad. In the 20th century Pisa once again began to flourish, thanks to the development of its university, trade, industry and, in more recent times, its fame among tourists worldwide.