The church of San Cesareo de Appia, commonly called San Cesareo in Palatio, is a church in Rome located near the Porta San Sebastiano, once the initial stretch of the Via Appia Antica, from which the "de Appia" designation. This church is of ancient origin: dates from the eighth century and was built on the remains of pre-existing Roman structures, which today can be seen in the basement (the remains of a floor mosaic with marine scenes of the second century A.D.). Over the centuries the church changed hands several times and was remodeled several times, it was completely restored in the sixteenth century by the Cavalier d'Arpino, and then entrusted to the Somaschi Fathers. On this occasion the thirteenth century mosaics were transferred here and other architectural furnishings that were in the transept of the Basilica of St. John Lateran, at that time under renovation. The interior has a nave, the side wall between the windows, are the work of the Cavalier d'Arpino mosaics depicting scenes from the life of San Cesareo. In the apse a mosaic that depicts God the Father among angels. The altar, the pulpit, the chair, the barriers of the presbytery are architectural elements that belonged to the Basilica of St. John: they are mostly composed of heterogeneous elements that date back to the thirteenth century.