Born in Rome, Rainaldi was one of the leading architects of 17th century Rome, known for a certain grandeur in his designs. He worked at first with his father, Girolamo Rainaldi, a late Mannerist architect in Rome. After his father's death, he fully embraced the monumental Baroque style. He gained ascendancy in Rome when the Barberini papacy of Pope Urban VIII was replaced by that of the more austere Pamphilj papacy of Innocent X. His works include the façade of Sant'Andrea della Valle (1661-65), the twin churches of Santa Maria dei Miracoli and Santa Maria in Montesanto, and Santa Maria in Campitelli (1663-67), considered his finest work. He was unable to complete the facade of Sant'Agnese in Agone during work in 1653-57.
Beyond his work as an architect in stone, Rainaldi also designed stage sets for religious rituals and events. In 1650, he designed the sets for the Quarant'ore, or Forty Hours Devotion, held in the church of Il Gesù. In 1665, he designed a catafalque commemorating the death of Philip IV of Spain.
Rainaldi died in Rome.
A rather young Carlo Rainaldi visited Grantville to learn about architecture from the town's library. Being a native born Italian and Latin speaker, Rainaldi needed a translator and tutor in which he met Emmanuel Onofrio and introduce to Joseph Jenkins. Rainaldi was taught under Jenkins and in the ensuing three months, he became far more interested in architecture in which he examined every buildings in Grantville including log cabins and trailers. Aside for his love of buildings, he was interested in a Lutheran girl named Angelina, who was pregnant with Rainaldi's child.
Rainaldi later visited Magdeburg where he received a letter in which he was overjoyed to learned that Angelina is coming to Magdeburg. He celebrated with his friend Thomas on buying drinks. In an unfortunate turn of events, Rainaldi was fatally wounded in the face by a wine bottle when an agitated anti-papist stone cutter was provoked by Thomas. Rainaldi was quickly taken to the USE Navy sick bay. He suffered a loss of his eye and his health his worsen from infection despite chloramphenicol were treated for his injuries. Inevitably Rainaldi was dying from the infection. His lover Angelina was able to arrive in which Admiral John Simpson decided to have them married before Rainaldi's death. When impressing a Lutheran and a Catholic chaplain, the latter refused to do marriage given Angelina is not of his parish and the former pointing the fact that the couple are Catholics and that the Lutheran Church won't recognize them. Instead, Simpson had Angelina officially recruited to the Marine Corps and a legal resident of the parish as Rainaldi has been in Magdeburg long enough to establish residency. The Catholic chaplain saw the marriage.
Rainaldi was considered deceased until David Dorrman performed CPR on the young man in which he was miraculously revived. A package was desperately sent from Grantville to Rainaldi which contains outdated penicillin to be treated for Rainaldi. Knowing what he is doing is illegal, Dorrman administered the drug on Rainaldi.