Adler was a German bicycle, automobile and motorcycle manufacturer from 1880 until 1957. The 'Adler' name is German for 'eagle'. Adlerwerke vormals Heinrich Kleyer (‘Adler Works formerly [known as] Heinrich Kleyer’) was a German manufacturer established by Heinrich Kleyer in Frankfurt am Main.
The factory in Frankfurt-Gallus still exists and was restored in the late 1990s for use as an office building. It also houses the Gallustheater and a restaurant.