沂源溶洞群位于山东省沂源县县城西北13公里、海拔1108.3米的鲁山南麓石灰岩山体中。在以千人洞为中心周围5平方公里范围内,分布着40余个天然洞穴,形成一个神奇的地下世界,被地质专家称之为“北国第一溶洞群”。在这些洞穴内不仅发现了距今约40～50万年前中更新世的猿人化石,还发现了旧石器文化遗址,因此,又被考古学家称为“沂源猿人溶洞群”。1985年以来,先后开发建设 Yiyuan karst caves located in Yiyuan County, Shandong Province, 13 kilometers northwest of the county, elevation of 1108.3 meters Lushan south limestone mountains. In the area around 5 square kilometers around the center of 1000 holes, there are more than 40 natural caves distributed, forming a magical underground world. Geological experts call it “the largest cave group in North China.” In these caves, not only the ape-man fossils dating back to about 400,000 to 500,000 years ago but also the Paleolithic cultural sites were discovered. Therefore, they were again called “Yiyuan ape-man cave group” by archaeologists. Since 1985, it has successively developed and built