What is so incredible about this site is to think that it was all basically destroyed in the Second World War and then painstakingly restored to exactly how it was before (for 40 years and at a cost of 20 million euros!).
The building is enormous and everything is so grand and beautiful inside. Unfortunately you can't take photos inside, but it does give you the chance to look at everything in detail and soak it up. It takes at least an hour to walk through and see everything - even longer if you are really careful.
Make sure you don't miss the gardens at the back of the residence (which are free to get into anyway). The landscaping is wonderful and I would suggest walking right up to the top at the back to get a view of the garden with the building to see how it all fits together.