Petrus is easily Pomerol's most important wine, and is one of the most notable estates in Bordeaux. Petrus is one of the world's most collectable and expensive wines. The vines at Petrus are allowed to reach an unusually old age by Bordeaux standards, and are only replanted after 70 years. The grapes are painstakingly hand-harvested – one berry at a time in the afternoon, after the morning dew has evaporated to avoid any dilution. Fermentation takes place in concrete vats, and vats are carefully scrutinized before assemblage.