By 1002, the ruin of the previous building had been razed and construction began on a new Romanesque structure designed by William, consisting of a subterranean church round the sarcophagus of Benignus, a ground floor church for worship, and a rotunda, 17 metres in diameter, on three levels in the place of the apse, linking the two. Dedicated in October 1016 by Lambert I, this suite of buildings was decorated in the ornate Cluniac style, of which only a few traces survive.
By 1002, the ruin of the previous structure had been demolished, and construction commenced on a new Romanesque edifice designed by William, comprising a subterranean church around the sarcophagus of Benignus, a ground-floor church for worship, and a rotunda, 17 meters in diameter, spanning three levels in place of the apse, connecting the two. Dedicated in October 1016 by Lambert I, this complex of buildings was adorned in the ornate Cluniac style, of which only scant remnants remain.