VENICE Venice will this week begin charging day trippers for entry, a world first aimed at easing pressure on the Italian city drowning under the weight of mass tourism . Tomorrow - a public holiday in Italy - day visitors will for the first time have to buy a five-euro ($5.3) ticket, monitored by inspectors carrying out spot checks at key points in the UNESCO world heritage site. Venice is one of the world's top tourist destinations, with 3.2 million visitors staying overnight in the historic