Contemporary, site-specific art in Italy can’t help but collide with an aggregation of artistic signs from the past; and when that happens, the boundaries between past and present are often blurred. Such was the case with Alessandra Tesi’s installation in Santa Maria della Scala in Siena, a Renaissance hospital still graced by fifteenth-century frescoes. Tesi’s intervention, entitled La Croce Verde (The green cross), 1998, played on both the art of fresco painting and the building’s historical function as a place for healing the body.

On the ceiling of one of the hospital’s long, gray, windowless