Columbia subject headings:
Harvard subject headings:
Fortification--Germany--Mainz (Rhineland-Palatinate)
Mainz (Rhineland-Palatinate, Germany)--History
Mainz (Rhineland-Palatinate, Germany)--History--Pictorial works.
Princeton subject headings:
Festung Mainz (Mainz, Germany)--History.
Fortification--Germany--Mainz (Rhineland-Palatinate)--History.
Mainz (Rhineland-Palatinate, Germany)--History.