What was the Musée d'Orsay in Paris used for before it was an art gallery?

Question

Which building on the Île de la Cité in Paris took 300 years to build from 1163, and was one of the first to have flying buttresses?

Answer 1

Railway station
The Gare d'Orsay, a Beaux-Arts edifice built between 1898 and 1900, served as a terminus for the Chemin de Fer de Paris à Orléans but by 1939 its short platforms had become unsuitable for the longer trains that had come to be used for mainline services, and it was closed to long-distance traffic, though some suburban trains of the SNCF continue to use its lower levels.