Take the Circle or District lines (yellow or green) to the Tower Hill stop. The exit from the Underground leads right to the Tower.
Admission to the Tower is £11 for adults and includes the opportunity for two free tours. The Royal Yeoman Warders (Beefeaters) give a overview of the tower tour and also a more in depth Punishment and Prisoner tour. The standard tour leaves every thirty minutes and ARE NOT TO BE MISSED!
The Beefeaters (who are retired, highly-decorated military officers) give an insightful, largely funny tour. During these tours you also gain access to the Chapel Royal of St. Peter. Other sights to be seen within the Tower include the Crown Jewels. A long queue leads you along corridors where you are shown scenes from Queen Elizabeth's cornonation and in-depth descriptions about the jewels. You can view some of the gold serveware on your own, but the actual jewels must be seen from people-movers. Because of the crowds, this is a great feature which allows you to get as close to the jewels as you are allowed without having someone standing directly in front of you. The White Tower holds an impressive collection of Royal Amouries. There are two gift shops on site and a cafeteria-style restaurant.
Do walk along the River Thames on your way out of the Tower and view the amazing landmark Tower Bridge.