The lavish gilded interior verges on the gaudy but it’s worth seeing through the bling for the Caravaggio paintings in the crowded chapel on the left. The left-hand panel shows Christ singling out the bewildered Matthew with a shaft of light, Matthew being dragged to his execution is on the right hand panel, while over the altar is an angel telling the bewildered evangelist what to write in his gospel. Caravaggio’s chiaroscuro technique can be seen to full brooding effect here. Don’t neglect the rest of the church: on the right transept are some Domenichino frescoes from the life of Saint Cecilia.