Its rebuilding was taken over by Wren in 1671 and mostly completed by 1684.
That building had nine bays incorporating a tower at the west end but, between 1762 and 1768, the two westernmost bays were demolished to allow for a widened pedestrian route through the base of the tower onto old London Bridge; the tower's lowest storey thus became a porch, and still is.
There have been many changes to the building since 1684. Finally, in 1924, the spacious, severe interior was restored in a neo-Baroque style to reflect its Anglo Catholic congregation.
The high altar is backed by a two storey reredos and flanked by two side chapels. On the north wall is a Russian icon, while in the south aisle stands a statue of St Magnus, holding a model of the church.
St Magnus also contains an extraordinary four metre long scale model of old London Bridge, with which it has been so intimately connected throughout the years.