The Hofburg is the former principal imperial palace of the Habsburg dynasty. Located in the centre of Vienna, it was built in the 13th century and expanded several times afterwards. It also served as the imperial winter residence, as Schönbrunn Palace was the summer residence. Since 1946, it is the official residence and workplace of the president of Austria. Since 1279, the Hofburg area has been the documented seat of government. The Hofburg has been expanded over the centuries to include various residences (with the Amalienburg and the Albertina), the imperial chapel (Hofkapelle or Burgkapelle), the imperial library (Hofbibliothek), the treasury (Schatzkammer), the Burgtheater, the Spanish Riding School (Hofreitschule), the imperial mews (Stallburg and Hofstallungen). The palace faces the Heldenplatz (Heroes Square) ordered under the reign of Emperor Franz Joseph I, as part of what was planned to become the but which was never completed. Numerous architects have executed work at the Hofburg as it expanded, notably the Italian architect-engineer Filiberto Luchese, Lodovico Burnacini and Martino and Domenico Carlone, the Baroque architects Lukas von Hildebrandt and Joseph Emanuel Fischer von Erlach, Johann Fischer von Erlach, and the architects of the Neue Burg built between 1881 and 1913. History The name translates as "Castle of the Court", which denotes its origins when initially constructed during the Middle Ages. Initially planned in the 13th century as the seat of the Dukes of Austria, the palace expanded over the centuries, as they became increasingly powerful. From 1438 to 1583, and again from 1612 to 1806, it was the seat of the Habsburg kings and emperors of the Holy Roman Empire, and thereafter until 1918 the seat of the Emperors of Austria. Since then the palace has continued in its role as the seat of the head of state and is today used by the Austrian Federal President. It is also the permanent home of the Organization for Security and Co-operation in Europe (OSCE). The whole palace complex is under the administration of the governor (Burghauptmann), who in turn is part of the Burghauptmannschaft, an office which has been in existence since the Middle Ages under the auspices of the Burgrave. At present the Burghauptmannschaft is under the jurisdiction of the Federal Ministry of the Economy. In September 1958, parts of the Hofburg were opened to the public as a convention centre. In the first ten years, the Burghauptmannschaft operated the convention centre; since