求翻译：京东大溶洞是爬山、攀岩、公路自行车等多种旅游运动项目的理想场所。京东大溶洞发育于中元古界，高于庄组白云岩地层，距今大约15亿年，是世界上目前发现的最古老的溶洞之一，由此号称“天下第一古洞”。4A级旅游区，是平谷接待游客最多、旅游收入最高的旅游景点。是什么意思？

Jing-dong da Cave was mountain-climbing, rock climbing, cycling and other sports an ideal place for tourism. Jing-dong da in the development of karst cave in Proterozoic, dolostones of the gaoyuzhuang formation, about 1.5 billion years ago, was discovered one of the oldest cave in the world, known as "the most ancient cave". 4 class a tourist area, is Pinggu hospitality, travel up to the top tourist attractions.