Complex sentence: It was rebuilt in Irish Romanesque style (c750) and the Great Nave was erected in the year 1220-indeed the roof timbers have been carbon dated by Queen's University Belfast to the year 1170.
Split into simpler sentences: It was rebuilt in Irish Romanesque style (ca.750) and the Great Nave was erected in the year 1220. The roof timbers have been carbon dated by Queen's University Belfast to the year 1170.