Cantores Cleveland isn’t just a chorus: It’s a cadre of veteran vocalists who perform the music of the Middle Ages, with a repertoire that includes madrigals, Latin liturgy, and early Baroque masterpieces. On a similar, ahem, note, downtown’s Trinity Cathedral isn’t just a church: It’s a trove of artistic treasures, including Renaissance paintings, sculptures from the Middle Ages, relics from the Holy Land, and two 15th-century stained-glass windows. Imagine tonight’s artistic synergy as the two cultural cohorts team up for The Pleasure of Sweet Harmony: a combination art exhibition and early-music concert happening inside the Gothic-style cathedral. The gallery opens at 6:15 p.m. The docent-lead tour begins at 6:45 p.m. And the narrated concert begins at 7:30 p.m. General admission is $10; reserve your spot via the website.