This architectural feature in Jerusalem appears in connection with David's and Solomon's building projects, representing either a terrace, rampart, or filled-in fortification. The term may describe a specific structure within David's city—perhaps supporting terraces on the steep slopes, or a citadel. Joash was assassinated at 'Beth-millo' or 'the house of Millo,' suggesting it had residential or administrative functions. The word's root meaning 'fill' led to various interpretations—a filled-in ravine, raised platform, or earthwork fortification. Archaeological remains show extensive terracing systems in ancient Jerusalem that may correspond.