Palace of Versailles

The owners of the building have recently put in a lot of lifts, which finally allow access to the upper floors (previously only the ground floor was accessible). The main courtyard outside is cobbled which you might struggle with, but once you are inside it's all smooth floors. I don't remember seeing many places to sit, so you may wish to borrow a wheelchair which you can do at the entrance (just ask reception). The place is very busy during the summers during the days so it could be a difficult sensory experience for those with sensory issues, so bringing some headphones is not a bad idea. As with all Parisian landmarks, there is an airport security-style metal detector arch & bag check, but you can skip the queues for these if you ask a member of staff. Unfortunately, I can't vouch for if the staff speak English or not, because I only interacted with them in French.