Did you know that the Eiffel Tower was once a giant advertising billboard? In the 1920s, the iconic Parisian landmark was used to display massive illuminated signs for the car company Citroën. The signs were so bright they could be seen from nearly 20 miles away, making it the world's largest advertisement at the time. Imagine visiting the Eiffel Tower today and seeing it lit up with neon logos! It's a fascinating reminder of how commercial interests have creatively utilized even the most unexpected places to reach audiences. Who knew the Iron Lady had such a flashy past?