A ten-minute walk outside the city walls brings you to the ruins of St Augustine's Abbey, one of the three parts of Canterbury's UNESCO World Heritage Site (alongside the cathedral and St Martin's Church). The footprint of the Anglo-Saxon and Norman church is laid out across a wide lawn — you can read the entire monastery plan from the surviving wall stubs, with English Heritage signage to interpret what you are walking on.
What survives above shoulder height is mostly Norman, including parts of the nave wall and the Fyndon Gate. The site museum is small but worth ten minutes for the early Christian artefacts found in the burials. The most evocative time to visit is late afternoon in autumn, when the long shadows make the ground plan unusually legible.