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When exactly was it built, and how long did it take?

Asked 26 Oct 2026 by ·Part of Who built the Great Pyramid, and how was the work organised?·2 answers·0·0 following
Answered: Built within Khufu's reign of about 26 years or more, in the 26th century BC.Passed its tests and review.

Where it stands

Two answers have been proposed. Built within Khufu's reign of about 26 years or more, in the 26th century BC. leads, with evidence 2 for, 1 against: supported by its tests. One is still possible.

Why it matters

The build time sets the labour arithmetic; the radiocarbon offset has been used to argue for an earlier date⁠[1]⁠[2].

Answers 2

Evidence: 2 for, 1 against
Most likely
None of these.
Failed a test; not refuted outright
Evidence: none yet
Disputed

History

  1. Bonani et al.: mortar dates from the pyramid itself average 100 to 200 years older than the historical date.Against: Built within Khufu's reign of about 26 years or more, in the 26th century BC.
  2. Bronk Ramsey et al. puts forward: built within Khufu's reign of about 26 years or more, in the 26th century BC.
  3. Bronk Ramsey et al.: the Oxford model agrees with the historical chronology within decades.For: Built within Khufu's reign of about 26 years or more, in the 26th century BC.
  4. Tallet: year 26 is the last attested year of Khufu and the pyramid was receiving casing stone then.For: Built within Khufu's reign of about 26 years or more, in the 26th century BC.
  5. Asked on this site
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