Astronomy Tower of the Sorbonne

Remember, a few days ago, I showed you the rue de Vaugirard in Paris.

Well, here is what you can see from its starting point:

This is the Astronomy Tower of the Sorbonne. It dates from the end of the 19th century and it still works. However, I always wondered how useful it was between light pollution and the almost constant blanket of clouds above the city.