On the exterior, the verticality is emphasised in a major way by the towers and spires and in a lesser way by strongly projecting vertical buttresses, by narrow half-columns called attached shafts which often pass through several storeys of the building, by long narrow windows, vertical mouldings around doors and figurative sculpture which emphasises the vertical and is often attenuated. The roofline, gable ends, buttresses and other parts of the building are often terminated by small pinnacles, Milan Cathedral being an extreme example in the use of this form of decoration.
What enhances the vertical look of the exterior of Gothic construction? 
the towers and spires