 The sinking ground and seismic activity of the area have had an effect on the cathedral 's construction and current appearance . Forty @-@ two years were required simply to lay its foundation when it was first built , because even then the Spaniards recognized the danger of constructing such a huge monument in soft soil . However , for political reasons , much , but not all , of the cathedral was built over the remains of pre @-@ Hispanic structures , leading to uneven foundation from the beginning . 
 The sinking ground and seismic activity of the area <a href='been_done' title='1'><mark>have</mark></a> had an effect on the cathedral <a href='null_genetive' title='2'><mark>'s</mark></a>construction and current appearance . Forty @-@ two years <a href='uninflect' title='3'><mark>were</mark></a> required simply to lay its foundation when it was first built , because even then the Spaniards recognized the danger of constructing such a huge monument in soft soil . However , for political reasons , much , but not all , of the cathedral was built over the remains of pre @-@ Hispanic structures , leading to uneven foundation from the beginning . 
The sinking ground and seismic activity of the area done had an effect on the cathedral  construction and current appearance . Forty @-@ 2 yrs was required simply to lay its foundation when it was first built , b/c even then the Spaniards recognized da danger of constructing such a bigass monument in soft soil . However , for political reasons , much , but not alll , of the cathedral was built ova the remains of pre @-@ Hispanic structures , leading to uneven foundation from the beginning .