"10 of the Best Castles on the Market Right Now"

They rather stretch the definition of 'castle', including this one which is better described by the agents as:

An Opulent Château - Southeast of Paris
Just 90 kilometres (56 miles) from Paris, this magnificent estate is situated in the heart of a forest on 700 private hectares (approximately 1,730 acres), encompassing woodland, lakes, and hunting grounds stocked with deer, wild boar, and pheasant...

That's going to cost you more than your typical fixer-upper donjon.

On the other hand this is one of the better sales pitches I've seen in a while:

...In addition to the main seven bedroom castle, the estate includes three separate properties - The Darnley and The Bothwell are self-contained cottages each with a living room, kitchen, three bedrooms, bathroom and WC. The Hideaway is a delightfully romantic suite hidden at the top of a turret spiral staircase.

The working stables at Seton have been magnificently refurbished and include a foaling stable. Adjacent to the stables lies the generous coach house and the characterful Stable Bar - the castle's authentic private tavern, situated in the original tack room of the stable block...

A secret bedroom?

From Country & Town House:

2. Earlshall Castle, St Andrews

Beautifully restored by Scottish architect Sir Robert Lorimer, this 16th century castle houses a world-famous walled garden and numerous spectacular reception rooms, all of them with unique and storied period features. Chief among them is the magnificent, 50ft painted ceiling in the Long Gallery, depicting coats of arms of European and Scottish noblity. Originally built by Sir William Bruce, the first Baronet of Kinross, Earlshall has hosted royal figures from Mary, Queen of Scots to King James I. Available through Savills, POA

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Related:
Tips For Buying Your Next Castle

....The 5000 acres probably bump the price a bit as well.

We made the same points regarding another Irish place, Lismore Castle:

Despite the crenelated battlements, and although the central keep looks real enough, the windows set into what should be curtainwall give away the fact that this is less castle and more comfy house.
This is what happens when upstarts like the Cavendish clan get their hands on stuff.

(just kidding Your Grace) 

The next thing to pay attention to is verticality.

This is from last June's "For Sale: English Tower That Rich Guy Built to Imprison Wife":

Again. not a true castle but as noted at the time:

And a fine tower it is.
Very vertical. 

The linked pictures lead to our third consideration, your spiral stairs. From the (maybe) adulterous wife tower above:...

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