During the Fourth Crusade in 1204, much of Constantinople and its priceless architecture was destroyed by the crusading Christian armies from western Europe. Following a lengthy siege, the Latin Christian armies broke through the city’s defences and sacked some of its most important sites, including the Hagia Sofia and Justinian’s tomb. Although the attackers were fellow Christians, the cultural differences that had developed during the long separation of the eastern and western churches meant that the sacking of the city was especially brutal. After Constantinople briefly became the centre of the Latin Empire, its prized monuments and buildings were largely neglected because funds were severely limited and had to be spent on the tenuous defence of the crusader empire. The emperor of Nicaea, John III, reportedly sent his own funds to the Latin Crusaders to ensure that they did not further desecrate important churches in their search for saleable materials.