The Tempietto of San Pietro in Montorio is a small martyrium, dedicated to St. Peter, designed by Donato Bramante in Rome.  The Spanish monarchs, Ferdinand of Aragon and Isabella of Castile, commissioned the building shortly after 1502.  The Tempietto is one of the first successes of High Renaissance architecture. 

Bramante was born in Monte Adrualdo, near Urbino.  Around 1474, Bramante moved to Milan and designed several churches in the new Antique style.  In 1476 the Duke, Ludovico Sforza, commissioned the rebuilding the choir of the church of Santa Maria presso San Satiro (1482-1486).  Space was limited, and Bramante created a theatrical apse in bas-relief, ultimately joining the painter’s tradition of perspective with Roman architectural details.  As with Brunelleschi's Pazzi Chapel, Renaissance architecture was born in Florence, so at Bramante's Santa Maria presso San Satiro, the Renaissance arrived in Lombardy.  However, in 1499, with his Sforza patron driven from Milan by an invading French army, Bramante made his way to Rome, where he was already known to the powerful Cardinal Riario who would later become Pope Julius II.
 
One of Bramante's earliest commissions has become known as one of the most harmonious buildings of the Renaissance: the Tempietto of San Pietro in Montorio.  The sanctuary was commissioned by Ferdinand and Isabella of Spain, and marks the spot in Rome on the Janiculum where, tradition has it, Saint Peter was crucified (this is probably a false perception as St. Peter was most likely crucified in the Circus of Nero).  The building is almost a piece of sculpture, for it has little architectonic use.  The interior is only large enough to hold 15 people.  Despite its small scale, the design represents a meticulous understanding of the traditional values of a Classical building.  Perfectly proportioned, it is composed of slender Doric columns, a Doric entablature modeled after the ancient Theater of Marcellus, and a dome. 

Tempietto: Bramante, 1502	Tempietto: Wood cut section and elevation, according to Palladio

According to an engraving in Sebastiano Serlio's Book III, Bramante planned to set the Tempietto within a colonnaded courtyard, but this plan was never executed.  The proposed courtyard has baffled architects and art historians for decades.  Due to its circular nature, the proportions that would have been required for the surrounding colonnade would not have fit within the existing site.  The resulting columns and spans would have also dwarfed the martyrium itself, thereby detracting from its importance.

Tempietto Floor Plan	Existing Tempietto Courtyard	Proposed Tempietto Courtyard

While some of the proposed ideas for the Tempietto have started many discussions on what should have been built, many people still find it to be one of the most important buildings of the High Renaissance.  Bramante’s Tempietto is still studied as a prime example of the Classical Revival during the Renassance and continues to provide a strong precedence for round monumental buildings.