An acropolis is defined as a city or portion of a city or territory that is fortified on top of something, such as the ancient Greek towns. The city of Athens, which was built on a fortified hill, is an example of an acropolis. The word comes from Greek akros meaning "highest" and -ouron meaning "wall." In modern usage, acropolis usually refers to the elevated fortress-city on Crete built by the Ancient Greeks. The word "acropolis" has been used in reference to many other sites around the world. One of the first uses of the term was by the French architect Michel-Ange Le Doare who in 1772 published a book entitled Architecture Ancienne et Moderne: Devoilé de la Grèce (Ancient and Modern Architecture: Revealed from Greece). In this work he describes several monuments in Athens that were probably early examples of acropoleis. Another early use of the term was by Edward Robinson, an English archaeologist who traveled in Greece from 1816 to 1820. In a letter written from Patras (Parthenon) in Peloponnese to his friend William Martin, Robinson describes an area near the city that contains remains of buildings that appear to have been constructed on top of one another like those in Athens. He calls this area "the Acropolis of Patras."