Santa Maria del Popolo
The architect or architects of this innovative project remain unknown due to a lack of contemporary sources. Giorgio Vasari in his "Lives" attributed all the important papal projects in Rome during Sixtus IV to a Florentine, Baccio Pontelli including the basilica and monastery of Santa Maria del Popolo. Modern researchers deemed this claim highly dubious and proposed other names among them Andrea Bregno, a Lombard sculptor and architect whose workshop certainly received important commissions in the basilica. The fundamental differences between the façade and the interior suggest that maybe more than one architect was working on the building.
Luigi Poletti (architect)
Poletti also added a choir to the Pantheon in 1840 and built the theaters in Fano (1845–1863), Rimini (1843–1857) and Terni (1840–1848). He rebuilt the church of San Venanzio in Camerino, which had fallen in the earthquake of 1792. After the damage from an earthquake in 1832, he rebuilt (1836–40) the Basilica of Santa Maria degli Angeli in Assisi. He built the Cathedral of Montalto delle Marche on the foundations that had been started under Pope Sixtus V. He designed the church of San Filippo in the town of Nocera (disambiguate?). He completed the chapel and altar of Santissima Maria (called dell'acqua) in San Francesco in Rimini. He built a similar chapel in Fossombrone. He designed the lighthouse and arsenal in the port of Ripa Grande. He designed the Palazzo Ceccopieri in Via di Monte Catino. He designed a number of funereal monuments in and around Rome including one dedicated to Vincenzo Casciani (1832) in the Costa Chapel, Santa Maria del Popolo and to the papal architect Cavalierie Pietro Bosio in the Campo Santo.