The Château de Chambord is an immense castle in France’s Loire River valley that boasts a treasure trove of stunning artworks and architectural wonders. One of the most impressive of these is a 16th-century double-helix staircase, located at the heart of the château, that allows visitors to ascend and descend at the same time without encountering each other on the steps. How does this remarkable staircase work? By its appearance, the double-helix staircase seems to be a single structure. In fact, it is composed of two separate spiral ramps that intertwine all the way up to the château’s crowning terraces, ...(100 of 887 words) Access the full article Help support true facts by becoming a member. Subscribe today!