Bologna was founded by the Etruscans. It is located in northern Italy, between the Po River and the Apennines. At one time, there were several layers of defense walls around the city, which were pretty successful at keeping away would be invaders. In 1088, the Studio was founded, which is now the oldest university in Europe. Bologna was one of the most populated cities in Europe in the year 1294, but a series of plagues set the population into a state of fluctuation. As the population grew back in the 20th century, the original defense walls were destroyed in order to make room for new houses. Parts of Bologna were destroyed during the end of World War II, but the city quickly recovered to become one of the richest and well planned in Italy.