Rouen Cathedral was the tallest building (the lantern tower with the cast iron spire of the 19th century) in the world (151 m) 495 feet! from 1876 to 1880.

Some details of the Architecture
Gothic except the romanesque crypt:
Early gothic:
Saint Romain's tower (12th century), side porches of the front, a part of the nave.
High gothic:
mainworks: nave, transept, choir, first floor of the lantern tower (13th century), side chapels, lady's chapel, side doorways (14th century)
Late gothic (flamboyant):
last storey of Saint Romain's tower (15th century), butter tower, main porch of the front, two storeys of the lantern tower (16th century)[1].
The Butter Tower was erected in the early 16th century.
Butter was banned during Lent and those who did not wish to forgo this indulgence would donate monies of six deniers Tournois from each diocesan for this permission.