ROME, ITALY—The church of Santa Maria Antiqua in the Roman Forum, one of the earliest Christian monuments in the city still standing, will reopen to the public for the first time since 1980. The fifth-century A.D. church has been closed while conservators restored the monument, known as the "Medieval Sistine Chapel," because of the vivid frescoes from numerous periods that cover its walls. The church was buried during an earthquake in 847 and was rediscovered by Italian archaeologist Giacomo Boni in 1900.