 Amiens Cathedral, begun in 1220 with the newer four-part ribs, reached the height of 42.30 meters (138.8 feet) at the transept.An important feature of Gothic architecture was the flying buttress, a half-arch outside the building which carried the thrust of weight of the roof or vaults inside over a roof or an aisle to a heavy stone column.The buttresses were placed in rows on either side of the building, and were often topped by heavy stone pinnacles, both to give extra weight and for additional decoration.