Stefon Diggs Rents Castle For Cardi B During French Vacation

Cardi B is getting the royal treatment -- Stefon Diggs hooked his lady up with an entire castle for their vacation in France ... where they'll be able to eat, sleep and poop like King and Queen!!

The rapper shared a tour of the temporary digs on her Instagram Story ... and the place comes complete with a moat, dining hall, indoor pool and themed bathrooms!!

During the walkthrough, Cardi cracked a joke about the toilet -- which looks like an elevated hole with a lid (don't worry, there's actual plumbing) -- saying, "this is where we take the royal s***" before panning to the tub, which is "where I will wash my royal hiney."

Cardi explained the inspiration behind the New England Patriots receiver's decision ... saying she previously complained about not having the time to check out castles whenever she's in Europe -- so he took matters into his own hands.

It's not all play for the NFL star, though -- he brought his trainer along for the trip ... and based on his own footage of the visit, he's busting his ass in some intense workouts.

Cardi seemed amazed by her man's work ethic ... even cheering him along as he lifted weights.

Pats fans have gotta love seeing this kinda content -- as opposed to the yacht vid that forced Diggs' employers to sit him down for a chat.