Modern architecture, conceived of as the elimination of ornament in favor of purely functional structures, left architects the problem of how to properly adorn modern structures. There were two available routes from this perceived crisis. One was to attempt to devise an ornamental vocabulary that was new and essentially contemporary. This was the route taken by architects like Louis Sullivan and his pupil Frank Lloyd Wright, or by the unique Antoni Gaudí. Art Nouveau, popular around the turn of the 20th century, was in part a conscious effort to evolve such a "natural" vocabulary of ornament.