You can easily allow yourself a whole day here. There is so much to see and it is all top quality. Step inside and you are immediately absorbed into another world. Something about England's historical past is encapsulated here. Not only in the architecture. The staff; the clergy; the way everyone seems to walk around in silent meditation. There are also beautiful paintings and sculpture by famous artists. Pre-Raphaelite painter Holman Hunt's 'The Light of The World' is here in all its splendour. The monotone paintings high up in the main cupola / dome are outstanding. I stood looking for ages and was happy to climb the 500-odd steps to get a closer look from the whispering gallery, where you can clearly hear words whispered 100 feet away on the other side of the dome. "Harry Potter", one young tourist was whispering. Quite chilling.
But for me it was the less obvious things that delighted. The wooden panelled vestibules where the choristers hang their cassocks. The cupboard that houses steps up into the organ pipes and pumps. The crypt is sheer bliss, with tombs of many famous musicians, painters, statesmen and Christopher Wren himself. The cafe and restaurant down here also serves delicious food.
Try to remember you are in the old city of London. When you leave, don't get straight on a bus or a tube. Have a walk around the back-streets. Here you'll find lovely old churchyards, warehouses and cobbled courtyards. You'll also find some excellent cafes, pubs and restaurants not aimed at tourists. These will help your day turn into something truly memorable.