This image was acquired from
wikimedia. It was marked as Public Domain or CC0 and is free to use. To verify, go to the source and check the information there.
Keywords from Image Description:
Akershus glacis . en Detail of Nser's map of Christiania showing the esplanade on the north side of Akershus fortress with scarp ditch counterscarp and glacis on the present Kontraskjret park no Kontraskjret Utsnitt av Nsers kart over Christiania Utenfor Hornverket nordsiden av Akershus festning vises graven kontreskarpen og glaciet