A reminder about the European Heritage Days taking place this coming weekend, (Saturday 19 and Sunday 20).
The program includes exhibitions, activities, and special openings of sites usually closed to the public, including over 300 special openings and tours in Paris. Most events are free, though some require a reservation.
The list of the thousands of scheduled events and tours is available on the official website (English version), which also features an interactive map.
https://journeesdupatrimoine.culture.gouv.fr/en/programme#/
Some examples
Exceptional opening of the Residence of the Ambassador of the United Kingdom
Visit to the American Church of Paris
The equestrian section of the Military School
Flash tour of the Arc de Triomphe