Complex sentence: A north chapel, believed to have been built using Italian marble altar reredos from Llantarnam Abbey, was erected, and was later referred to in 1535 as'chapel of St Michael near the monastry'.
Split into simpler sentences: A north chapel erected, believed to have been built using Italian marble altar reredos from the Llantarnam Abbey. The north chapel was later referred to in 1535 as'chapel of St Michael near the monastry'.