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Yelp
This is a distinctive, beautiful church, originally built in the twelfth century, and a wonderfully atmospheric location for the concerts that are frequently held here. It's well worth popping in to look at the interesting architecture, wall displays and video that is played for visitors. It's also the home of the Brass Rubbing Centre, and you can also leave from here for tours of Cambridge (which are not free, although entry to the church itself is).