The 11th and 12th centuries witnessed an explosion of building in medieval Europe, especially building of churches.
The cathedrals of the 11th/12th centuries were built in Romanesque style.
Romanesque churches were normally built in the basilica shape used in the construction of churches in the late Roman Empire.
Basilicas were rectangular buildings with flat wooden roofs.
Romanesque builders replaced the basilica’s flat wooden roof with a long, round stone arched vault (called a barrel vault) or with a cross vault, in which 2 barrel vaults intersected.
Because stone roofs were extremely heavy, Romanesque churches required massive pillars and walls to hold them up.
This left little space for windows, so Romanesque churches were dark on the inside and with massive walls and pillars these churches resembled fortresses.
A new style, called Gothic, appeared in the 12th century and was brought to perfection in the 13th.
The Gothic cathedral remains one of the greatest artistic triumphs of the High Middle Ages.
2 basic innovations made Gothic cathedrals possible.