The small city of Jena - population 100,000 - is an old university town in the German state of Thuringia. Almost every fifth inhabitant is a student. This mixture gives the city a youthful flair and vibrancy. Since the political revolution in East Germany, Jena has blossomed into an internationally significant center of learning and research. In addition to Friedrich Schiller University two Leibniz Institutes, three Max Planck Institutes and a Fraunhofer Institute are located in Jena. Although an atmosphere of change currently dominates, the city also proudly recalls the grand tradition of Goethe, Schiller, Hegel and Fichte, all of whom left their mark in its intellectual life. Johann Wolfgang von Goethe visited Jena from nearby Weimar many times. Friedrich Schiller, after whom Jena's ancient university was renamed, lived in Jena with his family. Ernst Abbe, Carl Zeiss and Otto Schott laid the foundations for economic prosperity based on the design and manufacture of superior microscopes and other precision optics. Located among limestone hills, the city is also a paradise for geologists and botanists. At least twenty-seven kinds of orchids can be found in the surrounding hills.