"Ponte Vecchio, the oldest of Florence's six bridges, is one of the city's best known images. Probably going back to Roman times with its stone pillars and wooden planks; it was built in stone but then newly destroyed by a flood in 1333. It was built again twelve years later, perhaps by Neri da Fioravante (or Taddeo Gaddi, according to Giorgio Vasari).
The five arches became three and the main part was widened. The shops, housed under the porticos, first belonged to the Commune which then rented them out. But later on, towards the 15th century, they were sold to private owners and began to change through subsequent additions, raised parts and external terraces, extending towards the river and altering the original architecture in an anarchical, suggestive way." - in: http://www.italyguides.it/us/florence/ponte_vecchio/old_bridge.htm
"In 1293, after the political success of the guilds, the new Priors wanted to build a monument which would become the most important civic monument in Florence, the Palazzo dei Priori, seat of the Signoria, later called Palazzo Vecchio. According to tradition, the central nucleus of the building was erected by Arnolfo di Cambio between 1299 and 1304.
It has the appearance of a fortress, topped by a huge open gallery, from which rises the slender tower known as the Arnolfo tower and which repeats in the belfry the design of the top of the palace. The two rows of elegant ogival mullioned windows; this is the only measured proportion to the Palace. It was subsequently enlarged by Vasari, in the sixteenth century and by Buontalenti, in the seventeenth century. Palazzo Vecchio, after having been the seat the seat of the town authorities, became the home of the Medici family.
Later it was the seat of the provisional governments (1848-49 and 1859-60), and when Florence was the capital of Italy from 1865 to 1871 it housed the Chamber of Deputies and the Foreign Ministry. It has been the seat of the municipal authority since 1872." - in: http://www.italyguides.it/us/florence/palazzo_veccchio.htm