What museum in Paris used to be the palace for the French king It now has a glass pyramid structure built in front of it.?

The museum you are referring to is the Louvre Museum, which originally served as a royal palace for French kings. The iconic glass pyramid, designed by architect I. M. Pei, was inaugurated in 1989 and serves as the main entrance to the museum. Today, the Louvre houses an extensive collection of art and historical artifacts, including The Mona Lisa and the Venus de Milo.