The Octagon is an eight-sided marble tomb on Curetes Street, and for about thirty years it was presented to the world as the grave of Arsinoë IV, Cleopatra’s murdered sister. In January 2025 a DNA and radiocarbon study settled the question: the bones belong to a boy of about 11 to 14, not to Arsinoë, and nobody knows his name.
Look at the building first. Among the monuments of the city’s grandest street it is shaped like no other: an octagon raised on a square podium, once ringed by Corinthian columns and capped with a pyramid roof. Excavators uncovered it in 1904. When Josef Keil opened the burial chamber in 1929 he found a sarcophagus with a skeleton inside and no inscription naming whoever lay there. Keil took away only the skull and left the rest of the body in the tomb, a decision that shaped the whole story that followed.
Why was the Octagon called the tomb of Cleopatra’s sister?
The history behind the theory is real. Arsinoë IV, younger sister and rival of Cleopatra VII, fought against Caesar in the Alexandrian war, was paraded in his triumph in Rome and then allowed to live in exile at the Temple of Artemis. In 41 BC, at Cleopatra’s request, Mark Antony had her killed at the sanctuary, a breach of sacred asylum that ancient writers recorded with distaste.
In the 1990s the Austrian archaeologist Hilke Thür joined the two threads. A princess killed in Ephesus would have needed a tomb, the Octagon’s shape seemed to echo the Pharos lighthouse of Alexandria, and earlier studies had described the skeleton as a girl in her mid to late teens. It made a compelling story, and by 2009 it had reached television audiences around the world. It was always a theory, though: nothing in the tomb ever named Arsinoë.
What did the 2025 DNA study find?
The skull Keil removed spent the 1930s moving between Greifswald and Vienna, was examined in 1953 and judged female, and then dropped out of sight for decades. Researchers found it again in a Vienna collection in December 2022 by matching it to archival photographs. A University of Vienna team led by Gerhard Weber then took DNA from the skull and from a thigh bone and published the results in Scientific Reports on 10 January 2025.
The DNA is male. The bones belong to a boy of about 11 to 14, radiocarbon-dated to between 205 and 36 BC, whose genetic ancestry points to the Italian peninsula or Sardinia. He also had serious developmental problems, including a skull suture that closed too early and a malformed upper jaw. Arsinoë IV is ruled out, and where her own body lies is still unknown. The dig that first opened the chamber is part of the long story told in how much of Ephesus has been excavated, which follows the work from 1863 to this 2025 result.
Pause at the Octagon anyway, on the lower stretch of Curetes Street a short walk above the Library of Celsus. The Arsinoë story is still worth hearing there, because it shows how a good theory grows, and how one skull that spent most of a century away from Ephesus could finally close the case.
