In 1660, François Draco Testa risked his life by entering the burning Church of Saint Francis in Constantinople (modern-day Istanbul, Turkey). Nearly two-thirds of the city was destroyed in the massive fire, which claimed more than 40,000 lives. The Genoese diplomat and dragoman (interpreter) François Draco Testa (1627–1709) succeeded in rescuing the double relic. Testa served the embassies of the Netherlands and Venice at the court of the Sultan. The reliquary contains a thorn from the Holy Crown of Thorns and a fragment of the True Cross—relics of great significance, as they are directly connected to the Passion of Christ.

François Draco refused to return the reliquary to the church. Eventually, Pope Pius VI ruled that the double relic could remain in the possession of the Testa family, as François Draco had saved it at the risk of his own life from the burning church. For centuries, the family remained active in the diplomatic circles of Constantinople, serving both the Ottoman sultans and the embassies of various European nations, including the Netherlands. The double relic was handed down through the generations. In the early twentieth century, Karl Victor Testa (1892–1943) inherited the double relic. He was married to Elisabeth Baroness Van Wijnbergen and lived in Amsterdam-Zuid. In 1939, he placed the double relic in his parish church, St. Agnes Church.

On March 30, 2025, Noepy Beckers-Testa transferred the double relic on loan to the Co-Cathedral Basilica of St. Nicholas, partly in honor of Amsterdam’s 750th anniversary.

“I find it important that the Testa Double Relic is accessible to a broad and international audience at a central location in Amsterdam. Thanks to my ancestor François Draco, the double relic was saved. It has made an extraordinary journey through world history—from Jerusalem, via Constantinople, to Amsterdam. It is a significant historical object that deserves to be seen.”