We visited Versailles as a day trip from Paris. It's less than an hour by train from the Gare Austerlitz and once you arrive in Versailles it's only about a five minute walk until you have this view.
I suppose this is the front door although the palace is so sprawling and has so many entrances that it's hard to tell. Entering the palace itself requires a ticket and basically leaves you in this courtyard where there are multiple different sections that can be visited. The main rooms are through the doorway under the French flag.
While much of the palace is off-limits to visitors you probably won't notice or care much because the furnished areas are still extensive. Like most French palaces and chateaus that existed pre-Revolution, this is actually 're-furnished' because it was looted during the Revolution.
Versailles existed as a hunting lodge for a long time but it was rebuilt into its current splendor by Louis XIV and then used as a royal residence until Louis XVI and the Revolution. That means only three French kings actually used this as their primary palace across just over a one hundred year span.
Probably the most famous 'room' in the palace is the Hall of Mirrors. The primary purpose of this room was simply to connect the King's quarters with the Queen's quarters. There were of course balls held here as well. As best we can tell there were balls held everywhere inside and outside Versailles.
As big as the palace itself is, the grounds dwarf it in size. They may well be as large as the modern town of Versailles itself. This is a view of the palace from the back. The Hall of Mirrors occupies most of the middle floor of that central building looking out onto these reflecting pools.
This is the nice 'little' side garden at Versailles. The primary gardens extend back from the rear of the palace and eventually bring you to other buildings including the Trianon palaces, originally built for assorted mistresses. Also found out there is a recreated Norman village from the 1780s used by Marie Antoinette and her court to 'play' at being peasants.
The Latona fountain has a central view of the gardens and the palace and represents the story of Latona from Metamorphoses.
From the side of the fountain you can see down the alleyway to the so-called "Grand Canal" of Versailles. It's not so much a canal as a rectangular pool. Nowadays you can rent boats and float around out there but it's relatively limited space.
To either side of the alley behind these giant hedge walls are all sorts of nooks and crannies tucked into formal gardens. It's a great place to wander around and you'll periodically find fountains, statues, colonnades and quite possibly a restaurant or two (there's actually one on each side).