There is a fee; but worth it. The beautiful building and history makes this a must see. The climb to the top is a undertaking, and not for the weak of heart, or legs. Several of the stairwells are very narrow and low. If you have a problem with tight places, don't climb to the very top level. But, if you make it all the way, the views are wonderful! I would think this is the best place to get a great view of the skyline of London. On the way down don't forget to look through the glass floor which looks directly down into the middle of the dome into the Cathedral. Make sure to wander around St. Paul's and take it all in. The ceilings are amazing! Down into the crypt you'll find bathrooms, a cafe, and tombs including Nelson's. If you have a little extra time after finishing you tour, sit in the park outside an enjoy the atmosphere!