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.
In 1002, the previous building was demolished, and construction began on a new Romanesque structure designed by William. This structure included a subterranean church around Benignus' sarcophagus, a ground-floor church for worship, and a rotunda spanning three levels in place of the apse, connecting the two. Dedicated in October 1016 by Lambert I, this complex was decorated in the ornate Cluniac style, with only fragments remaining today.