Shop owners in the early 20th century had an ever-greater amount of merchandise for sale and display. Also, the growing number of department stores needed taller buildings and large open-plan spaces. Architects used the latest technologies of steel frames and large sheets of plate glass to meet this demand. Electric lighting and reflectors, concealed above the ceilings of display windows, replaced gas lighting, making window displays more attractive. Fashionable styles, from Beaux-Arts classicism to neo-Georgian, and even quirky styles like Art Deco Venetian and Tudor Revival, were used.