Heritage Open Day: Visit St Mary Coslany Church in Norwich, a round tower church dating from the 11th century, now home to Mander Auctioneers & Valuers. Come and talk to local church experts and have your jewellery, art, antiques and collectables valued for free. St Mary Coslany Church in Norwich is a round tower church dating from the 11th century. Having been closed to the public the last few years it is now home to Mander Auctioneers & Valuers. Come and visit the church, with experts from the Round Tower Church Society, Michael Polis and Richard Banergh, on hand to answer any questions you might have about the building. Auctioneer Dylan Mander will also be giving free valuations of jewellery, art, antiques and collectables.