The Serapeum, long and wide, was divided in three sections: a rectangular area could be accessed first by walking under monumental arches; an open square, adorned with red granite obelisks brought to the city during the 1st century and erected in couples, followed. The centre of the square was likely occupied by the temple dedicated to Isis, while the third section, a semicircular exedra with an apse presumably hosted the altar dedicated to Serapis. Fragments of the obelisks, some quite large, have been found around the current church of Santa Maria sopra Minerva; some archaeologists have proposed that the obelisk facing the Pantheon (see picture) may have been repositioned from the temple to its current location.