Temple of Serapis

On the northern slope of the Quirinal Hill, inside what are now the Colonna Gardens, the ground preserves the memory of one of Rome’s most ambitious lost sanctuaries. No temple stands here today, but the terraces, brick retaining walls, and staircases cut into the hillside reveal a structural system built to manage a steep drop toward the Campus Martius below. Rather than leveling the slope, Roman builders worked with it, creating a sequence of platforms that guided visitors upward toward a temple that once crowned the summit.

That temple is identified as a sanctuary of Serapis, the Greco-Egyptian deity whose cult spread through the Mediterranean as Rome absorbed religious traditions from its eastern provinces. The identification rests on converging evidence: ancient literary references to a Serapeum on the Quirinal, the scale of the surviving substructures, and a terraced plan that recalls eastern sanctuaries such as the Serapeum of Alexandria and the sacred terraces of Pergamon. Scholars have long debated its date. Nineteenth-century archaeologists including Christian Hülsen attributed the complex to the Severan dynasty, but a detailed reassessment by Rabun Taylor argued instead for a Hadrianic origin, with the grand staircase and portico added later under the Severans. This account follows that Hadrianic reading, part of a broader second-century pattern of incorporating foreign cults into Rome’s religious landscape.

The topographer Rodolfo Lanciani mapped the sanctuary’s likely footprint across this slope, and Renaissance draughtsmen recorded architectural fragments, including a pediment that apparently still stood, visible on the skyline, into the medieval period. Sculptural evidence reinforces the reconstruction. Colossal river-god figures representing the Nile and Tiber, now on the Capitoline Hill, along with the Dioscuri in Piazza del Quirinale and the battered figure known as Madama Lucrezia near Piazza San Marco, are thought to derive from the sanctuary’s decorative program. Some scholars propose these figures once formed part of an enormous pedimental composition, with an enthroned Serapis at its center flanked symmetrically by monumental attendants, though the precise arrangement remains debated.

Physical evidence for the temple’s scale survives on site. Among the fragments preserved in the Colonna Gardens is a pedimental corner block of roughly one hundred tons, cut from Proconnesian marble quarried in the Sea of Marmara and shipped to Rome for major imperial commissions. Positioned originally more than thirty meters above ground, the block testifies to the cranes, rigging, and organized labor that construction on this scale required.

The sanctuary’s decline followed a familiar Roman trajectory: abandonment as the cult faded in late antiquity, partial survival through the Middle Ages, and systematic stripping during the Renaissance, when the site became a source of building material rather than a monument. Marble from the Serapeum’s stair system is thought to have been reused in the medieval staircase leading to Santa Maria in Aracoeli on the Capitoline, a route still walked today. The Colonna family’s later garden, laid out over the terraces, preserved rather than erased the underlying Roman framework, leaving a sanctuary that survives not as a standing building but as a landscape still legible to those who know how to read it.

Further reading

1. Taylor, Rabun. “Hadrian’s Serapeum in Rome.” American Journal of Archaeology, vol. 108, no. 2, 2004, pp. 223–66. JSTOR, http://www.jstor.org/stable/40025232. Accessed 3 July 2026.
2. Coarelli, Filippo. Rome and environs: an archaeological guide. Univ of California Press, 2007.
3. Versluys, Miguel John. Aegyptiaca Romana. Nilotic Scenes and the Roman Views of Egypt. Vol. 144. Brill, 2015.
4. Brennan, Brian. “RODOLFO LANCIANI AND THE SOUTHWEST QUIRINAL: FROM EXCAVATION TO THE FORMA URBIS ROMAE.” Papers of the British School at Rome, vol. 91, 2023, pp. 241–71. JSTOR, https://www.jstor.org/stable/27331999. Accessed 3 July 2026.