The document discusses the evolution of Gothic architecture from the 12th century onwards. Some key developments included ribbed vaults that distributed weight along walls, pointed arches, and flying buttresses that supported thick walls and vaults. Examples discussed include early Gothic cathedrals like Saint-Denis and Notre Dame in Paris, as well as later Gothic structures like Amiens Cathedral, Sainte-Chapelle, and Milan Cathedral, demonstrating Gothic architecture's spread across Europe over centuries.