Yes, you can go inside the Elizabeth Tower, which houses the Great Bell famously known as Big Ben, but the access rules are quite specific and depend on your residency status. For UK residents, tickets are made available through a booking system on the UK Parliament website, and tours are free but must be booked well in advance due to extreme popularity. For international visitors, there are limited paid tour slots that allow you to climb the 334 stone spiral steps to the top of the tower. These tours take you behind the four clock faces and provide a close-up view of the mechanism and the massive bells. It is important to note that the climb is physically demanding and there is no elevator, so visitors must be in good health. Following a massive multi-year renovation that concluded recently, the interior is more accessible than ever, but security remains very tight. You cannot simply walk in off the street; a pre-booked ticket and a security screening are mandatory for every guest wishing to see the inner workings of London's most iconic landmark.