The Forum of Constantine dates to around 330 CE, when the emperor moved the empire's capital east and stamped his name on a new city. His forum occupied the ridge of what is now the Çemberlitaş neighborhood — a location still marked, faintly, by the Column of Constantine, which stands a short walk away. The forum remained a feature of Byzantine urban life for centuries, though its precise fate in later Byzantine times is uncertain. Western travelers mentioned a church, or perhaps a monastery, somewhere on the site. By the time Ottoman builders arrived, the forum's fourth-century stones had long been absorbed into the city's foundations. What they constructed above those foundations was not a conversion of something older but something fully new.

The han's builder was Atik Ali Pasha — Hadım Ali Pasha — a vizier who served Sultan Bayezid II. He had already funded a mosque and complex in the Çemberlitaş neighborhood, with the mosque and its mausoleum on one side of the main avenue (the ancient Mese, today Yeniçeriler Avenue) and a madrasa and the han on the opposite side. An Ottoman decree preserved in the Topkapı Palace Museum Archives dates the commission to around 1510–11. Ali Pasha was killed in 1511, fighting on the eastern front, so construction must have been well advanced before his death. The inn was built, it appears, on the site of Ali Pasha's own residence, damaged in the catastrophic earthquake of 1509 — a personal loss transformed into a charitable foundation that would generate income for the mosque complex in perpetuity.

The name Elçi Han — literally 'Ambassador's Inn' — suggests the han hosted diplomatic visitors to the Ottoman capital. How that use came about is unclear; caravanserais routinely served whoever arrived with the means to pay. Later historians, including the prominent scholar İsmail Hakkı Uzunçarşılı, proposed that the building was once the Venetian Balyos Han, a lodging for the Venetian baili — the republic's resident ambassadors — but this identification is now rejected. Venetian diplomats stayed elsewhere in the city. What the name does suggest is that by the time Evliya Çelebi visited in the 17th century and described it, the han had an established reputation for hosting foreign dignitaries. Çelebi's claim that the building was of Byzantine origin and rebuilt in 1456 is also contradicted by the archival record — the han was Ottoman-built from the start.

One of the most vivid firsthand descriptions of the Elçi Han comes from Hans Dernschwam, a German traveler and merchant who stayed there between 1553 and 1555. Dernschwam was a meticulous observer; his published account of the Ottoman capital noted the han's function and its founder's fate — he recorded that Ali Pasha died fighting the Persians, a detail that aligns with the historical record. The han clearly remained in operation through the mid-sixteenth century, functioning as intended: a resting place for visitors from distant places, a node in the vast network of Ottoman commercial and diplomatic life. What happened to it after that — when it was demolished, whether it was replaced by something else — the sources do not say.

The site today sits along one of Istanbul's most-walked streets, within easy reach of the Grand Bazaar and the Column of Constantine. No physical trace of the han remains visible. But the stratigraphy below the pavement is extraordinary: Roman forum fill, unidentified vaulted structures that may be remnants of Constantine's original construction, then the Ottoman caravanserai built over all of it, and now the modern city overhead. The Elçi Han is a ghost building in the fullest sense — gone from sight, impossible to visit, but precisely located and historically documented. It survived long enough for a German merchant to sleep there and write about it, and for an archival decree to record its commission. Sometimes that is enough.