A court of honor (cour d'honneur ; Ehrenhof) is the principal and formal approach and forecourt of a large building. It is usually defined by two secondary wings projecting forward from the main central block (corps de logis), sometimes with a fourth side, consisting of a low wing or a railing. The Palace of Versailles (illustration) and Blenheim Palace (plan) both feature such entrance courts. Technically, the term cour d'honneur can be used of any large building whether public or residential, ancient or modern, which has a symmetrical courtyard laid out in this way. Some 16th-century symmetrical Western European country houses built on U-shaped groundplans resulted in a sheltered central door in a main range that was embraced between projecting wings, but the formalized cour d'honneur is first found in the great palaces and mansions of 17th-century Europe, where it forms the principal approach and ceremonial entrance to the building. Its open courtyard is presented like the classical permanent theatre set of a proscenium stage, such as the built Roman set of opposed palazzi in a perspective street at Palladio's Teatro Olimpico (Vicenza, 1584). Like the theatre set, the built environment is defined and enclosed from the more public space by ornate wrought iron gilded railings. A later development replaced the railings with an open architectural columnar screen, as at Palais Royal (Paris), Schönbrunn Palace (Vienna), Alexander Palace (Saint Petersburg), or Henry Holland's Ionic screen formerly at Carlton House, London (illustrated below). Examples of a cour d'honneur can be found in many of the most notable Baroque and classicizing buildings of Europe including the Palazzo Pitti, one of the first 16th century residences to open a cour d'honneur in the Pitti's case by embracing three sides of an existing public space. Other 16th century urban palazzi remained resolutely enclosed, like Palazzo Farnese, Rome. In Rome, the wings of Carlo Maderno's Palazzo Barberini design (1627), were the first that reached forward from a central block to create a cour d'honneur floorplan.