With the Industrial Revolution, the material chosen were more likely wrought, cast iron or, later, reinforced concrete. In this way, also the shape of the infrastructures started to change. Some example of curved structures were the Palm House, Kew Gardens by Richard Turner and Decimus Burton and the The Crystal Palace by Joseph Paxton, or on the infrastructures side, the Garabit viaduct by Gustave Eiffel. Later in 20 century, Pier Luigi Nervi started studying the possibilities of reinforced concrete, building his famous ribbed hangars.