Map of neighborhood surrounding the area where the chalice was found (circled in red). Possible places of origination include the parish church of St. Olave towards the Tower (green), Crutched Friars Friary (blue), and St. Mary Grace's Abbey (black).
This is a map, depicting the southwest corner of the medieval city of London, shows the location of Baynard's Castle and its dock where the brooch was found.