If you want to feel holy then you should pay a visit to the Saint Paul's Cathedral. You are going to end up praying for everything in your life when you visit this cathedral. This cathedral is one of the most beautiful cathedrals in the world. If you think that you have seen nice churches then you should go to this one. You are going to fall in love with this church right when you enter it. If you go to London and then you do not have a picture with the Saint Paul's Cathedral then you are going to feel lacking.