 St Edern 's is medieval in origin , with later additions and alterations . The oldest part is the nave , which has been described as " essentially 14th @-@ century " , although it was rebuilt in 1871 during restoration work under Henry Kennedy , architect of the Diocese of Bangor . It was one of many churches in Anglesey to be rebuilt or restored in the 19th century – few remained untouched – and Kennedy was responsible for much of the work carried out from the 1840s to the 1890s . The north wall was rebuilt above the tops of the windows , whereas only the bottom 2 to 3 feet ( 0 @.@ 6 to 0 @.@ 9 m ) of the south wall was left unaltered . During this work , some of the nave windows inserted in the 15th century were repositioned , and a chancel ( at the east end ) , a porch ( south @-@ west corner ) and a transept or side chapel ( north @-@ east corner of the nave ) were added . The " extensive " work cost about £ 1 @,@ 000 . 
