posted 05-22-2003 01:40 PM            

well according to the guinnes book of records is Castle of Prague the largest:

Largest Ancient Castle
The largest ancient castle in the world is Prague Castle in Prague, Czech Republic, built in the 9th century. It is an oblong irregular polygon with an average diameter of 128 m (420 ft), giving a total surface area of 7.28 hectares (18 acres).

http://www.guinnessworldrecords.com/index.asp?id=50103

It also says that Windsor Castle is the largest inhabited castle:

Largest Inhabited Castle
The royal residence of Windsor Castle at Windsor, Berkshire, UK, is originally of 12th-century construction and is in the form of a waisted parallelogram measuring 576.164 m (1,890.540 ft) all around.

http://www.guinnessworldrecords.com/index.asp?id=50101

So now we only have to find two other large castles from the middle ages. I think the Kremlin in Moscow (Russia) is a good candidate and an other one would be possible Bernburg in Germany, or Höhkönigsburg in France of Burghausen in Germany (which at least is the longest castle of the world).