Let's compare Hamburg to a very beautiful woman: her beauty and all her charms are immediately visible at first glance. However, a beautiful exterior alone is not enough to captivate in the long term. It takes more: history, experience, and yes, also secrets. And Hamburg has plenty of those. Many of them have faded into obscurity precisely because the gaze tends to linger on the grand, obvious advantages. For instance, in the courtyard of the town hall, one is more likely to admire the magnificent façade than to notice the small, stone kitchen boy carved above a window, licking a spoon. And one does not look into the light shaft at the post office on St. Stephen's Square either – how could one guess that it contains two pipes, which are the last remnants of the pneumatic tube system that once ran under Hamburg?.