Località Bivio Capodacqua incrocio con Colle S. Giacomo , Capestrano, (L'Aquila)
The church of San Pietro ad oratorium, put under the jurisdiction of the wealthy Abbey of San Vincenzo al Volturno in Isernia, was founded in the eighth century by order of King Desiderius and entirely re-built in the twelfth century in Romanic style. The plan of the church consists of a nave and two aisles divided by two rows of round arches with three extrados apses; the façade, made up of regular stone blocks, is the original one as far as the lateral naves and has a big portal decorated with flowers and spirals. Inside the church there are a thirteenth-century ciborium and a cycle of frescoes covering the apse and the triumphal arch, representing Christ, the evangelists and the twenty-four old men mentioned in the Apocalypse. On the external wall of the church there is an outstanding stone block, called the Magic Square because of the inscription engraved in it: ROTAS OPERA TENET AREPO SATOR, whose meaning has not been definitely cleared yet. According to the most likely interpretation, the phrase is a cryptographic palindrome, that is an expression that reads the same forwards and backwards; moreover, its anagram contains the words PATER NOSTER. On the architrave of the portal there is the inscription: A REGE DESIDERIO FUNDATA MILLENO CENTENO RENOVATA, that is "founded by King Desiderius and renovated in 1100".