R to L:The walling by the women is defensive walling on the motte.
The wall remains immediately below and to the left of the above,is the remains of the entrance gate to the motte summit.
In the middle distance is a curved earthen mound,with traces of walling on top.That is the remains of the eastern bailey wall.
SEE http://www.ecastles.co.uk/castleacre.html
see http://www.castlexplorer.co.uk/england/acre/acre.php#castle
see http://www.castleuk.net/castle_lists_east_anglia/132/castleacre.htm