 Because of the muddy subsoil of the site , work on the foundation continued past the work on the walls to 1581 . In 1585 , work on the first of the cathedral 's chapels began and by 1615 , the cathedral 's walls reached to about half of their final height . Construction of the interior of the current cathedral began in 1623 and what is now the vestry was where Mass was conducted after the first church was finally torn down . 
 Because of the muddy subsoil of the site , work on the foundation continued past the work on the walls to 1581 . In 1585 , work on the first of the cathedral <a href='null_genetive' title='1'><mark>'s</mark></a>chapels began and by 1615 , the cathedral <a href='null_genetive' title='2'><mark>'s</mark></a>walls reached to about half of their final height . Construction of the interior of the current cathedral began in 1623 and what <a href='drop_aux' title='3'><mark>is</mark></a>now the vestry was where Mass was conducted after the first church was finally torn down . 
Because of the muddy subsoil of da site , wrk on the foundation continued past the wwrkon the walls to 1581 . In 1585 , work on the first of the cathedral  chapels began and by 1615 , tdacathedral  walls reached to bout half of their final height . Construction of thdanterior of the current cathedral began in 1623 and what now the vestry was where Mass was conducted after thedarst church was finally torn downn .