Are most Historic Cathedrals built - on or near - the 40th parallel?
Christianity started in Europe "around the 40th parallel", so many churches and so cathedrals were built there. But there are historic (Romanesque, Gothic, medieval and later) cathedrals in whole Europe and not only around the 40th parallel. For example the Cologne Cathedral (Gothic cathedral) is near the 50th parallel and its very first beginnings were in the Roman era (former buiding). Another example of an very old cathedral with beginnings in Roman times is Canterbury Cathedral near the 51th parallel. The Gothic cathedral of Notre-Dame-de-Paris is near the 48th parallel and not that near the 40th parallel either. There are also very old cathedrals in Russia. There are also (newer) historic cathedrals in other continents.
Gothic architecture - Wikipedia
en.m.wikipedia.org
Lists of cathedrals - Wikipedia
en.wikipedia.org