[3] Christiansen curated and or coordinated many exhibitions at the museum including: The Age of Caravaggio (1985), The Age of Correggio and the Carracci (1986–87), Caravaggio's Cardsharps Rediscovered (1987), Andrea Mantegna's Descent into Limbo (1988), Painting in Renaissance Siena: 1420–1500 (1988–89), A Caravaggio Rediscovered: The Lute Player (1990), Andrea Mantegna (1992), Jusepe de Ribera (1992), Giambattista Tiepolo (1996–97), From Van Eyck to Bruegel: Early Netherlandish Painting at The Metropolitan Museum of Art (1998–99), Donato Creti: Melancholy and Perfection (1998), Orazio and Artemisia Gentileschi (2001–2002), El Greco (2003–2004), From Filippo Lippi to Piero della Francesca: Fra Carnevale and the Making of a Renaissance Master (2005), Raphael at the Metropolitan: The Colonna Altarpiece (2006), Poussin and Nature (2008), and Michelangelo's First Painting (2009).
In June 2020 Christiansen ignited a bit of a firestorm including within the ranks of Metropolitan Museum's own staff when he published an Instagram post decrying the destruction of monuments by "zombies".
Therein a letter was sent to the museum's leadership by staff members asking for recognition of "what we see as the expression of a deeply rooted logic of white supremacy and culture of systemic racism at our institution.” A day before the staff letter was sent Christiansen apologized to the European paintings department calling his Instagram post "not only not appropriate and misguided in its judgment but simply wrong.” Christiansen had uploaded a picture of a pen and ink drawing by the archaeologist Alexandre Lenoir (1769–1831) of his efforts to try to save monuments during the French Revolution and had the caption "Alexandre Lenoir battling the revolutionary zealots bent on destroying the royal tombs in Saint Denis.
How many great works of art have been lost to the desire to rid ourselves of a past of which we don’t approve"...[2] Christiansen is the co-author with Judith W. Mann of Orazio and Artemisia Gentileschi (2001) from the Met Publications.
[4] Christiansen edited From Filippo Lippi to Piero della Francesca: Fra Carnevale and the Making of a Renaissance Master (Met publications 2005) as well as contributing an essay to the volume.