The Church of the Nativity in Bethlehem is one of the oldest continuously operating churches in the world. The structure is built over the cave that tradition marks as the birthplace of Jesus of Nazareth, and thus it is considered sacred by Christians. The site is also revered by followers of Islam (Wikipedia).
St. Catherine's Monastery. The site contains the world's oldest continually operating library, possessing many unique books including the Syriac Sinaiticus and, until 1859, the Codex Sinaiticus. A small town with hotels and swimming pools, called Saint Katherine City, has grown around the monastery.