Locating Jerusalem’s Millo

The tower built to protect the Gihon Spring was constructed using enormous limestone blocks, resulting in an imposing system of walls nearly 23 feet thick. Photo: Nathan Steinmeyer

Central to the development of Jerusalem in antiquity was the Gihon Spring, which provided the city with a year-round source of fresh water. The spring is situated near the bottom of the western slope of the Kidron Valley, which runs north–south along the eastern edge of the city. Over the centuries, beginning in the Middle Bronze Age (c. 2000–1550 BCE), a variety of means were developed for accessing the spring, including the digging of Hezekiah’s Tunnel in the late eighth century BCE, which channeled water into the heart of the city.

Naturally, a chief concern of Jerusalem’s inhabitants was the protection of the Gihon Spring. This water source was so precious that the emerging settlement developed on what would later be known as the City of David, just above the spring, rather than on the more defensible hilltop to the north that would eventually become the Temple Mount. It is hardly surprising, then, that excavations in the late 1990s and early 2000s revealed substantial fortifications built around the spring.

According to archaeologists Chris McKinny, Aharon Tavger, Nahshon Szanton, and Joe Uziel, these fortifications provide a ready answer to a longstanding biblical mystery. They present their view in the Fall 2023 issue of Biblical Archaeology Review in the article “The Millo: Jerusalem’s Lost Monument.”

The Millo is referenced in several places in the Hebrew Bible. We learn a variety of key facts about the Millo from these sundry references: it was a significant, imposing, and apparently enclosed royal structure (2 Kings 12:20); it was located on the periphery of the City of David, and was associated with but somehow distinct from the city’s fortifications (2 Samuel 5:9; 1 Kings 11:27); it appears to have existed before Jerusalem became the capital city of Judah (2 Samuel 5:8–9); and it was repaired and renovated by various Judahite kings through the late eighth century BCE (2 Chronicles 32:5).

Despite these details, however, the identification of the Millo has remained elusive. The name itself comes from the Hebrew root ml’ (meaning “to fill”) and for the past 200 years, scholars have assumed this meaning must be related to the character or function of the Millo itself. The 19th century saw a variety of proposals emerge that identified various Jerusalem pools as possible candidates, including the Siloam Pool, which is fed from the Gihon Spring by way of Hezekiah’s Tunnel. These proposals failed to yield a scholarly consensus, however.

Following excavations by Kathleen Kenyon in the 1960s, this stepped structure on the east side of the City of David was widely believed to be the Millo. Photo: Nathan Steinmeyer

The landscape shifted in the 1960s with Kathleen Kenyon’s excavations of the City of David. Working along the western slope of the Kidron Valley, she discovered an extensive terraced wall system that led her to propose a novel idea: the “filling” associated with the Millo involved dirt, not water. Consensus rapidly grew that this area, which was “filled” with layers of stone and soil construction, was the Millo.

Our authors question this theory, however, noting that the Hebrew verb ml’ rarely relates to a stone or earthen filling. Indeed, all but two uses of the term in the Bible appear in conjunction with water or other liquids. Instead, they argue the fortifications excavated around the Gihon Spring are a more plausible candidate for the Millo—not as a place that is filled with water, but as a site where people would go to fill their water containers.

This “Spring Tower,” as it is known, matches all the clues presented in the various biblical references to the Millo. Built with immense limestone blocks and walls several feet thick, it certainly qualifies as monumental architecture, mentioned with pride alongside the palaces of David and Solomon. It would make sense to mention it in conjunction with the city’s other fortifications, given the importance of protecting the Gihon Spring. Additionally, our authors argue that the original construction may well date to the Middle Bronze Age, with subsequent renovations occurring periodically but especially during the time of the Judahite kings.

Given this evidence, the authors deduce that the search for the Millo has ended at the Spring Tower, which protected the city’s water source for centuries. Only time will tell if this theory gains widespread acceptance, but it certainly seems to hold water.

To learn more, read Chris McKinny, Aharon Tavger, Nahshon Szanton, and Joe Uziel’s article “The Millo: Jerusalem’s Lost Monument,” published in the Fall 2023 issue of Biblical Archaeology Review.

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Subscribers: Read the full article “The Millo: Jerusalem’s Lost Monument” by Chris McKinny, Aharon Tavger, Nahshon Szanton, and Joe Uziel in the Fall 2023 issue of Biblical Archaeology Review.