Architectural movement (c. 1730–c. 1930) most commonly associated with Romanticism. The first nostalgic imitation of Gothic architecture appeared in the 18th century, when scores of houses with castle-style battlements were built in England, but only toward the mid-19th century did a true Gothic Revival develop. The mere imitation of Gothic forms and details then became its least important aspect, as architects focused on creating original works based on underlying Gothic principles. French architects, particularly E.-E. Viollet-le-Duc, were the first to think about applying the Gothic skeleton structure to a modern age. Though the movement began losing force toward the end of the century, Gothic-style churches and collegiate buildings continued to be constructed in Britain and the U.S. well into the 20th century.