Exploring Tower Bridge in its entirety typically takes around 1.5 to 2 hours. This allows ample time to walk across the high-level walkways, visit the Engine Rooms, and enjoy the panoramic views. If you're particularly interested in the history and machinery, allocate extra time for the Engine Rooms. Keep in mind that wait times for the bridge lift schedule, if you want to witness it, might add to the overall duration. Overall, a couple of hours should suffice for a comprehensive visit to this iconic London landmark.