The castle was expanded several times to house the growing number of Knights. Soon, it became the largest fortified Gothic building in Europe, on a nearly site. The castle has several subdivisions and numerous layers of defensive walls. It consists of three separate castles - the High, Middle and Lower Castles, separated by multiple dry moats and towers. The castle once housed approximately 3,000 "brothers in arms". The outermost castle walls enclose , four times the enclosed area of Windsor Castle. The developed part of the property designated as a World Heritage Site is .