was one of numerous experienced and loyal civil servants employed by the duke. Seckendorff was considered one of the most able and influential thinkers on administration and public law of his time. His book Der teutsche Fürstenstaat (1656), written by order of Ernest, served for decades as a standard work in teaching political science at Protestant universities in Germany. Friedenstein Castle was built between 1643 and 1654 and is one of the first large Baroque residence castles in Germany. Between 1657 and 1676, the city received a stronger fortification, which was demolished between 1772 and 1811. In their place, a park around Friedenstein and a boulevard around the city were established. Some important scientific institutions were the ducal library (today's Forschungsbibliothek Gotha as part of the University of Erfurt), founded in 1650, the "coin cabinet" (1712), the "art and natural collection", basis of today's museums, and the Gotha Observatory at Seeberg mountain, established 1788. The Gotha porcelain manufactory (established in 1767) was famous around 1800 for their faiences. In 1774, the actor group led by Conrad (or Konrad) Ekhof, called "the father of German acting", came from Weimar to Gotha. He began working at the Schlosstheater and became Direktor of the first ever German court theatre (founded in 1683), while acting in many plays himself. Having turned it into one of the leading theatres in Germany, after his death in 1778 the fame of the theatre declined rapidly. The Almanach de Gotha, a directory of European royalty and nobility, was first published in 1763 and Justus Perthes founded his science publishing company in 1785. Joseph Meyer followed in 1826 by founding the Bibliographisches Institut, one of the two leading encyclopedia publishers in the German language besides the Brockhaus and Adolf Stieler first published his Handatlas in Gotha in 1816. Johann Adam Weishaupt, the founder of the order of the Illuminati, died in Gotha in 1830. It was also during this time, that the city developed a sizeable Jewish population. Since 1815 From 1826 to 1918, Gotha along with Coburg was one of the two capitals of the Duchy of Saxe-Coburg-Gotha. Under the rule of Duke Ernest II, Gotha was a centre of Germany's liberal movement, where the Gothaer Nachparlament, an aftermath of 1848 German Revolution took place. After 1851, Gustav Freytag, novelist, advocate of German unity and often a harsh critic of Otto von Bismarck made Siebleben (today part of