Plans for a “sunken” cafe and bar in the shadow of an ancient castle have raised fears among conservationists. The ultra modern-designed licensed eatery is earmarked at a car park where the wall formed part of Rochester Castles’ original medieval gatehouse and is on a site steeped in centuries of history. In the middle of a designated Ancient Monument Area, archaeologists have unearthed artefacts dating back to Roman and medieval times over the years. In a report to Medway Council’s planning committee, expert Chris Butler said: “There is potential for any groundworks to damage or destroy natio…