Complex sentence: In around 970 Bishop Gratias encouraged the building of a new cathedral in the Romanesque of which all that is left today of the 12th-century cathedral of Tréguier is the north transept tower known as the "Hastings" tower.
Split into simpler sentences: In around 970 Bishop Gratias encouraged the building of a new cathedral in the Roman style. All that is left today of the 12th-century Romanesque cathedral of Tréguier is the north transept tower known as the "Hastings" tower.