The city was heavily damaged by air raids in 1945, especially on March 22. Although it had little military significance, two months before the end of the war in Europe the historic city was bombed as part of the Area Bombing Directive in order to undermine the morale of the German people. 28.5% of the houses were completely destroyed and 44.7% damaged. 26.8% of the houses remained undamaged. The centre, which had retained its medieval character until then, was almost levelled. As in many cities, priority was given to rapid building of badly needed housing, and concrete structures took the place of the destroyed buildings. Fortunately, most of the major churches, two of them now UNESCO World Heritage Sites, were rebuilt in the original style soon after the war. During the war, valuable world heritage materials had been hidden in the basement of the city wall. In 1978, the University of Hildesheim was founded. In the 1980s a reconstruction of the historic centre began. Some of the unattractive concrete buildings around the marketplace were torn down and replaced by replicas of the original buildings. In the fall of 2007, a decision was made to reconstruct the Umgest�lpter Zuckerhut ("Upended Sugarloaf"), an iconic half-timbered house famous for its unusual shape
