Starting today, les Journées du Patrimoine is a special event that allow you to access to usually closed cultural site in the city. Some of the museum also open their door for the whole night (or nearly) !
Here is a link to a map that includes all events. Just zoom in Paris and see if one of them is close to your hotel ! http://traduction.culture.gouv.fr/url/Result.aspx?to=en&url=https://journeesdupatrimoine.culture.gouv.fr/Programme