The woman in this video, Melinda Kathleen Reese sings O Come O Come Emmanuel three times in this church, the Iglesia de la Encarnación in Montefrío, Spain. It’s misnamed in the video and incorrectly linked to another Spanish church in her Wiki page: it’s a Catholic church that was built between 1786 and 1802 and was modeled after the Pantheon of Agrippa in Rome, hence its circular shape.

Judging from the look of pure joy and wonderment on her face I think it’s because she’s loving the acoustics. This was an impromptu performance by the American singer in 2018, hence her casual dress. But who cares about that when you have the voice of an angel in the season of Advent.