For most of the twentieth century the Pool of Siloam that appears in first-century accounts of Jerusalem was known from texts and assumed to be somewhere near a small Byzantine-era basin that had long carried the name.
In 2004 infrastructure work at the southern end of the City of David cut into a flight of stone steps. Ronny Reich and Eli Shukron excavated across 2004–05 and found the real thing: a large stepped pool of the Second Temple period, at the bottom of the slope, exactly where the pilgrim route up to the Temple Mount would have started.
That relationship is the point. The pool is not a detail of the city, it is the first move of a sequence — immerse at the bottom, ascend the monumental southern stair, arrive at the platform. Herod’s builders designed the arrival, and the arrival began at the water.