The Fortezza Vecchia (the Old Fortress) was constructed by the Venetians in the aftermath of the Turkish invasion of Corfu in 1537, greatly expanding the existing defences there. The fortress successfully withstood two subsequent Turkish sieges, in 1571 and 1716.

This plan appears to show the fortress as it was about the time of the third siege, of 1716.

It is pasted onto a sheet with manuscript drawing of a compass, with wind directions, and another fortification.