Beijing vendors are becoming more aggressive in their tactics to secure tourist dollars. Touts pace foreign tourists at landmarks throughout the city pestering them with drinks, maps or food, often overcharging. Even areas previously regarded as away from the tourist traps are in danger of losing their tranquil charm. Built to ward off marauding Mongolians, the Simatai Great Wall has now been invaded by persistent postcard sellers. Postcard sellers stand alongside the Kunming Lake walkway at the Summer Palace, shouting English to catch foreigners' attention. People without proper tour guide licences offer to escort foreign visitors through the Forbidden City. A director with China International Travel Service, which arranges trips for foreigners, said site managers sometimes allowed vendors access if they were friends or made a payment. 'It's a management problem,' said Liu Weiqiang, director of marketing. 'The best place for vendors would be a set stand. In a developed country you'd have these.' He said tourists were most concerned about safety and fair prices and they could find both in China. Airport management bureau manager Tao Runmin said airport authorities often checked for illegal taxi drivers but they kept coming back. He said the airport would solve the problem before the 2008 Olympics.