thumb|250px|A model of the [[Apostolic Palace, which was the main project of Bramante during Sangallo's apprenticeship.]]
thumb|250px|The church of Santa Maria di Loreto near the [[Trajan's Market in Rome.]]
thumb|250px|The [[Villa Farnese in Caprarola; the initial design was by Sangallo and Baldassare Peruzzi.]]
thumb|250px|[[San Giovanni dei Fiorentini; Sangallo was responsible for the foundation projecting out into the Tiber.]]
thumb|250px|View of [[Pozzo di San Patrizio|St. Patrick's Well in Orvieto.]]
Antonio da Sangallo the Younger (12 April 14843 August 1546), also known as Antonio Cordiani, was an Italian architect active during the Renaissance, mainly in Rome and the Papal States. He worked on the design of St. Peter's Basilica in the Vatican City, and was also an engineer who restored several buildings. His success was greatly due to his contracts with renowned artists during his time. he ended up taking the name ″Sangallo″ and then becomes known as Antonio da Sangallo (the younger). Instead of becoming an apprentice to an artist, his apprenticeship consisted of doing carpentry work. Due to his success, Sangallo was eventually put in charge of the Passetto di Borgo between the Papal apartments and the Castel Sant'Angelo. That particular project was left unfinished, but it left Sangallo with a working reputation as an architect.
Independent commissions
Sangallo quickly received a major commission for the church of Santa Maria di Loreto in 1507. His design called for a square first story and an octagonal second story built in travertine and brick; the dome and lantern were finished many years later. Although Leo X's papacy enabled Sangallo to connect with great artists, his main encouragement came from Cardinal Alessandro Farnese (later Pope Paul III). He likely learned arithmetic and Latin at this time, which would influence his complicated calculations in his later projects. He practiced "operative criticism," which looked at architecture through a historical and societal lens. The members of the Sangallo circle had a variety of experiences and skills that ranged from building tools, pumps, and mills to building entire canals, buildings, and even moving the Vatican obelisk.
Antonio designed his projects in six stages. Although the model that Sangallo designed for the church was never built, the construction of Giacomo della Porta's designs began later, in 1583.
Another project was the Basilica della Santa Casa in Loreto. The church had not originally been built well, with cracking vaults and an unstable foundation. Sangallo redesigned the church and shored up the foundations; Vasari claims the church to be ″the best that Antonio ever executed″ despite the challenges innate in rebuilding a church as opposed to building a new one from the ground up. Sangallo was also hired to do similar work on the Vatican loggias, which had shown signs of weakness due to poor construction; his reinforcements stand today.
Sangallo was also a noted military architect, working on the fortifications of numerous cities such as Parma, Piacenza, Ancona and Orvieto. In Orvieto, he was also tasked by Pope Clement VII with building a well, called Saint Patrick's Well, noted as a marvel of engineering. Its double-helix ramps around a central open shaft allowed oxen carrying water to go down via one of the ramps and up via the other without having to turn around. Despite its 175-foot depth, the ramps are well lit through windows cut into the centre section. Possibly an inspiration for the design, the Well of Joseph in the Cairo Citadel also featured a double spiral staircase. [previous sentence not changed but added citation] One of the most significant projects for Antonio’s career was to design and build the Fortezza da Basso in 1534. Sangallo the Younger almost completed the project in two years for the new Imperial Duke of Florence, Alessandro de' Medici. Previously, the Basilica was entrusted to Antonio's uncle, Giuliano da Sangallo. It was after the sack of Rome that Antonio da Sangallo was responsible for its undertaking, with construction of the Basilica beginning in April 1506.
thumb|Palazzo Farnese in Rome
thumb|Drawing of St. Peter's Basilica
Selected works
- Basilica della Santa Casa in Loreto.
- Cappella Paolina, the Sala Regia and the Scala Regia in the Vatican.
- Old Fortress, Livorno.
- Palazzo Baldassini in Rome.
- Palazzo del Governatore di Borgo in Rome, demolished in 1936.
- Palazzo Farnese in Rome (1534–46), designed for Cardinal Alessandro Farnese.
- Palazzo Sacchetti on the Via Giulia in Rome; designed by Sangallo for himself.
- Saint Patrick's Well in Orvieto.
- Santa Maria di Loreto in Rome.
- San Giovanni dei Fiorentini in Rome.
- St. Peter's Basilica in Rome (chief architect from 1520 on).
- Villa Madama in Rome (started 1518).
- Cappella Paolina, the Sala Regia and the Scala Regia in the Vatican.
- Palazzo Colonna (Marino)
Death and legacy
Sangallo's final project was on the Rieti Valley, which had been commissioned to him by Pope Paul III. After working in the marshy environment, Sangallo contracted malaria and died in 1546 before finishing his work. Sangallo is buried in St. Peter's Basilica with the following epitaph:
<poem>
: ANTONIO SANCTI GALLI FLORENTINO, URBE MUNIENDA AC PUB.
:OPERIBUS, PRAECIPUEQUE D. PETRI TEMPLO ORNAN. ARCHITECTORUM
:FACILE PRINCIPI, DUM VELINI LACUS EMISSIONEM PARAT, PAULO PONT.
:MAX. AUCTORE, INTERAMNAE INTEMPESTIVE EXTINCTO ISABELLA DETA
:UXOR MOESTISS. POSUIT 1546, III. CALEND. OCTOBRIS.
</poem>
His biographer Vasari writes, ″In truth Antonio, who was a most excellent architect, deserves to be celebrated and extolled, as his works clearly demonstrate, no less than any other architect, whether ancient or modern.″ As an architect, his legacy can be seen through the buildings he worked on, especially as they inspired future architectural methods. His existing drawings serve as insight for other architects who can hope to learn from his architectural forms.