[lo_zamoyski]

The trouble is that the definition of "castle" varies considerably between countries. For instance, the German classification divides them into "Schloss" and "Burg", but these can include anything from earthworks to barely present ruined remains of a foundation to buildings that resemble a larger than average house. French classification - under the term "chateau" and its subdivisions - is even more generous. Compare that with the Polish classification which is more strict and precise, differentiating between manors, palaces, strongholds, and permanent fortified complexes, for instance.

[rob74]

Sure, you could argue forever what should be included, what's significant enough (only still existing buildings or also ruins? how well-known does it have to be?), if only historical castles should be included or also things like Hearst Castle in California (which is actually a large mansion built in historical style, with the main building looking like a church - if that's included, you could also include, say, Mar-a-Lago?).

[uxhacker]

It is also important in context to include castles in Africa to show that the area did contain castles. This fact often surprises people that Africa has castles and some of them dating back to the 11 century.

For example just by looking from my eye you are missing Lamu Castle https://en.wikipedia.org/wiki/Lamu_Fort Siyu Fort https://en.wikipedia.org/wiki/Siyu Thimlich Ohingahttps://en.wikipedia.org/wiki/Thimlich_Ohinga

And then in Tanzania you have the Gerezani Fort in Kilwa Kisiwani, the Old Fort of Zanzibar, the German Fort in Bagamoyo. And then Taleh Fort in Somalia.

I have not even started on either Mozambique, or Angola.

[uxhacker]

The importance of the definition is to actually save the castles. For example in Lower Silesia in Poland, which was Germany, and Czech before, there where about 2000 Castles (Schloss's). Now many of these castles lay in ruins. By only including the popular ones like this map does it means the less famous ones will become even less popular, and a piece of history will disappear.

[twic]

An Italian friend was excited to visit a castle, and on arrival disappointedly exclaimed "but this is a "fortezza!".