Jerusalem and Mecca are probably the most famous pilgrimage destinations of the Near East. But how one can recognize the pilgrimage in the archaeological record? In the past, archaeologists laid a stress on small findings that testify to the pilgrimage movement: cultic artifacts, pilgrims' souvenirs, foreign coins and imported pottery vessels that were brought to the sites. Nevertheless, it seems that there are more recognizable landmarks in the Holy Cities. The analysis which is offered here is based on Jerusalem of the Late Second Temple period, and Mecca of the 19th century, i.e., before the introduction of modern technology. We suggest to recognize a more obvious trace of pilgrimage movement: an anomaly in the water systems. More precisely, it resolves that big unroofed water pools signal for the function of the site as a pilgrimage destination.