Every year, it is open in August and September, so we need to make an online reservation in advance. But the guard change ceremony was also very good. An hour's guard change ceremony began at 11:15 a.m. The process is that the guards and cavalry go from a distance to Buckingham Palace, and then change their posts for about half an hour (only when they stand close to the palace's perimeter railings can they see what's going on inside). Then the guards and cavalry would come out of the gate and leave one after another. So if you want to see inside and outside clearly, the best observation point is at the iron railings on both sides of the middle gate (but not nearly an hour in advance). Next is the opposite side of the road facing the gate (including the front of the high steps of the middle Victorian statue), where you can see a part of the interior in addition to the queue, which can barely be seized more than half an hour in advance. The rest is the front row of the railings everywhere, where you can clearly see the queue passing.