Two Trecento Treasures at Koller
On 18 September 2026, Koller Auktionen in Zurich brings two rare Italian gold-ground panels on the art market as part of its A218 Old Master Paintings sale. Founded in 1963, Koller is Switzerland's 🇨🇭 leading auction house and one of the most respected names in continental Europe for Old Master paintings, regularly placing significant early Italian works with museums and private collections alike. This September's sale includes two small but historically rich panels — a newly identified fragment by a major Sienese master, and a Florentine predella panel with a documented trail back through some of the 20th century's most notable private collections.
Agnolo Gaddi, Saint Elizabeth of Thuringia with Roses
The second lot is an even smaller jewel: a predella panel of Saint Elizabeth of Thuringia, attributed to Agnolo Gaddi (c. 1350–1396), painter, mosaicist, and son of Taddeo Gaddi — himself Giotto's foremost pupil. Measuring 23 × 21 cm and retaining its original gilded frame, the panel likely once formed one of the outer corner elements of a now-lost Florentine altarpiece, flanking the base of its side pilasters.
Prof. Freuler's analysis links it stylistically and technically to two other predella panels from the same altar complex: a Saint Anthony of Padua that surfaced on the Rotterdam art market in 2023, and a Saint Margaret of Antioch held today in the Metropolitan Museum of Art in New York. Together, the Franciscan iconography and the emphasis on female saints point to an origin in a Poor Clares' church. The panel's provenance is unusually rich for so small a work, passing through the collections of Charles Loeser in Florence, Dr. A. Steinheim in Amsterdam, the Paris dealer Heim-Gairac, and the Rotterdam collection of Loeff-Visser before entering a European private collection.
Estimate: CHF 40,000 / 60,000 (EUR 41,240 / 61,860)
Taddeo di Bartolo, Saint Mark with the Winged Lion, c. 1410
The first lot is a recently rediscovered fragment attributed to Taddeo di Bartolo (1362–1422), one of the leading painters of the Sienese school in the early Quattrocento. Executed in tempera and gold ground on panel and measuring just 37.5 × 21 cm, the panel depicts Saint Mark with his attribute, the winged lion.
What makes the piece especially compelling is its recent scholarly rehabilitation. Identified in 2024 by Dr. Orazio Lovino as part of Taddeo di Bartolo's dismembered 1418 polyptych for the high altar of the Dominican church of San Domenico in Gubbio, the panel fills a gap in a reconstruction first proposed by Dr. Gail Solberg back in 1994 — a reconstruction that placed the fragment's original position between figures of Matthew and Thomas Aquinas, above a fragment now in the Snite Museum of Art in Indiana. The attribution has since been confirmed by both Lovino and Solberg, and the work is accompanied by a fresh art-historical analysis from Prof. Gaudenz Freuler (July 2026). The Gubbio altarpiece is considered Taddeo di Bartolo's last major commission and the culmination of his late style.
Estimate: CHF 20,000 / 30,000 (EUR 20,620 / 30,930)
Both lots go under the hammer at Koller Zurich on 18 September 2026. As always with works still in the pre-sale phase, prospective bidders should conduct independent research and due diligence.
