Gothic art originated from Romanesque art and lasted from the mid-12th century to the 16th century. The Gothic era in painting spanned more than 200 years, starting in Italy and spreading to the rest of Europe. Towards the end of this period there were some artists in parts of the North who resisted Renaissance influences and kept to the Gothic tradition. As a result, the end of the Gothic timeline overlaps with both the Italian and the Northern Renaissance timelines. Architecture was the most important and beautiful art form during the Gothic period. The main structural characteristics of Gothic architecture came out of masons' efforts to solve the problem with supporting heavy ceiling vaults over wide spans. The problem was that the heavy stonework exerted a large pressure that tended to push the walls that the vault rested on, making them collapse. So, a building's supporting walls had to be made extremely thick and heavy in order to contain the vault's pressure. The round arches of the barrel vault were replaced by pointed, Gothic, arches which evenly distributed the pressure in more directions. These elements made it easier for masons to build much larger and taller buildings than their predecessors and to give their structures more complicated designs. The Gothic style began with the architecture of the 12th century when Europe was putting the memory of the “Dark Ages'' behind it and moving into a new era of prosperity and confidence. Very beautiful Gothic cathedrals were built in towns such as those in the northern French towns of Chartres, Reims and Amiens. As for painting, the change to the new style became apparent around a century after the first of these cathedrals were built. In contrast to the Romanesque and Byzantine styles, the biggest feature of the art of the Gothic period is its increased naturalism. This quality became the dominant painting style throughout Europe until the end of the 15th century.