The situation changed with the Venice Charter for the Conservation and Restoration of Monuments and Sites ( 1964 ) .
In 1973 the Schnoor became a historic district under official heritage conservation through the State Monument Authority .
The situation changed with the Venice Charter for the Conservation and Restoration of Monuments and Sites ( 1964 ) so that in 1973 the Schnoor became a historic district under official heritage conservation through the State Monument Authority .