Scholarly reconstruction
Ai is et-Tell; the story explains the ruin
The impressive Early Bronze ruin inspired a story of its conquest.
Source: J. A. Callaway, excavations at et-Tell (Ai), 1964–1972
Ancient Mysteries & Interpretations
Ai, "the ruin," is usually identified with et-Tell near Bethel, a great Early Bronze Age city destroyed about 2400 BC, followed by a small Iron Age village: no city in either proposed period of Joshua. Advocates of an early conquest argue that Ai is Khirbet el-Maqatir, a small site nearby with a claimed Late Bronze I fortress.
Identification: disputed · et-Tell: does not fit · Maqatir: advocacy proposal

"Ai, which is beside Bethaven, on the east side of Bethel" (Joshua 7:2). "Joshua burnt Ai, and made it an heap for ever, even a desolation unto this day" (8:28).
Et-Tell: excavated by Judith Marquet-Krause (1933–35) and Joseph Callaway (1964–72). Early Bronze city, destroyed c. 2400 BC; abandoned; small unwalled Iron I village (12th–11th centuries BC).

Khirbet el-Maqatir: excavated by the Associates for Biblical Research (Bryant Wood, 1995–2000; Scott Stripling and others, 2009–2016), who report a small Late Bronze I fortress destroyed by fire and argue it fits a 15th-century conquest. Critics question the site's size, dating and the identification of Bethel (Beitin vs el-Bira) on which the geography depends.
Scholarly reconstruction
The impressive Early Bronze ruin inspired a story of its conquest.
Source: J. A. Callaway, excavations at et-Tell (Ai), 1964–1972
Traditional reading
A small fortress fits Joshua 7:3 ("they are but few") and a 15th-century date.
Assessment: An alternative supported mainly by its excavators.
Source: Associates for Biblical Research, "The Search for Joshua's Ai" (advocacy of Khirbet el-Maqatir) ↗
Scholarly reconstruction
Neither site is correct, or Bethel is misidentified.
No site has been securely identified as Joshua's Ai in the conquest period. The two proposals are presented as alternatives, not as the same confirmed place.
What the evidence shows
Source: J. A. Callaway, excavations at et-Tell (Ai), 1964–1972
Source: Associates for Biblical Research, "The Search for Joshua's Ai" (advocacy of Khirbet el-Maqatir) ↗