One of my favorite small museums in Europe stands hidden in plain sight, fronting a leafy square in the exquisite little city of Colmar. The Unterlinden Museum has long ranked among Alsace’s greatest cultural jewels, a status only enhanced by its elegant expansion in 2015. Acclaimed architectural firm Herzog & de Meuron (designers of Hamburg’s Elbphilharmonie, Beijing’s Bird’s Nest stadium and London’s Tate Modern) vastly increased the museum’s square footage and created a new public space in the city. The design turned what had been a bus station and parking lot into an inviting square, partially bisected by the reopened Sinn Canal.

Two of the museum’s stars remain on display in the original space, a converted 13th-century convent. The most famous is the extraordinarily expressive and harrowing “Isenheim Altarpiece” by Matthias Grünewald, one of the greatest works of German Renaissance painting, displayed in the convent’s former chapel. Grünewald created this crucifixion scene for a monastery hospital, where many of the patients suffered from skin diseases. To show Jesus’ empathy for their plight, Grünewald painted his skin covered in welts. Jesus’ fingers contort in agony, blood drips from his mangled feet, and his loincloth is in tatters. A gray-faced Mary faints into disciple John’s arms, and below her, an anguished Mary Magdalene kneels in fervent prayer. Emphasizing the hellish quality of the scene, a bleak and blasted landscape extends behind the figures, unrelieved by a single shred of vegetation. Don’t miss the rear of the altar, where one panel depicts a suspicious-looking Mary during the Annunciation, and another on which Jesus floats above terrified soldiers in a psychedelic vision of the Resurrection. When we visited, we were able to watch restorers at work on other panels in a glass-walled enclosure just behind the altarpiece.

In a side room of the convent is another of the museum’s stars, the late 15th-century “Orlier Altarpiece” by local artist Martin Schongauer. This vibrantly colorful work doesn’t have the raw emotionality of the “Isenheim Altarpiece,” but it merits close inspection just the same. Schongauer painted the people in each scene with great sensitivity, making each one seem like an individual, not a symbol. Certain panels depict the same sort of surreal demons and monsters that one might find in a Hieronymus Bosch painting.