<P> Bramante's finest architectural achievement in Milan is his addition of crossing and choir to the abbey church of Santa Maria delle Grazie (Milan). This is a brick structure, the form of which owes much to the Northern Italian tradition of square domed baptisteries . The new building is almost centrally planned, except that, because of the site, the chancel extends further than the transept arms . The hemispherical dome, of approximately 20 metres across, rises up hidden inside an octagonal drum pierced at the upper level with arched classical openings . The whole exterior has delineated details decorated with the local terracotta ornamentation . </P> <P> In Rome Bramante created what has been described as "a perfect architectural gem", the Tempietto in the Cloister of San Pietro in Montorio . This small circular temple marks the spot where St Peter was martyred and is thus the most sacred site in Rome . The building adapts the style apparent in the remains of the Temple of Vesta, the most sacred site of Ancient Rome . It is enclosed by and in spatial contrast with the cloister which surrounds it . As approached from the cloister, as in the picture above, it is seen framed by an arch and columns, the shape of which are echoed in its free - standing form . </P> <P> Bramante went on to work at the Vatican where he designed the impressive Cortili of St. Damaso and of the Belvedere . In 1506 Bramante's design for Pope Julius II's rebuilding of St. Peter's Basilica was selected, and the foundation stone laid . After Bramante's death and many changes of plan, Michelangelo, as chief architect, reverted to something closer to Bramante's original proposal . </P> <P> Antonio da Sangallo the Younger, (1485--1546), was one of a family of military engineers . His uncle, Giuliano da Sangallo was one of those who submitted a plan for the rebuilding of St Peter's and was briefly a co-director of the project, with Raphael . </P>

Who commissioned this building why was it placed on this particular spot and who was the architect