The Uffizi Gallery was created within a building which Cosimo I de'Medici commissioned to house the judiciary of the citys guilds beside his residence in Palazzo Vecchio. His heir, Francesco I, initiated a collection of portraits of famous men, both historic and contemporary , on the top floor during the 1580s and created the first nucleus of today's museum in the octagonal Tribune, entered from the first corridor. Francesco housed the most precious and fabulous works of art and rarities of nature in the Tribune. The collection of scientific instruments and the Medici armoury were later displayed in neighbouring rooms. In the centuries that followed, the Medici and then the Lorraine continued to add collections of artm and these now constitute one of the most important museums in the world.