Out of a stately old bell tower with carved pinnacles projects a pair of old stone walls with Roman arches, iron-hinged doors, a gable and even an angel statuette, welcoming you home to Church Court at 492 Beacon St. in the Back Bay with ceremonial sanctity. At first, this may feel like you're going to church or meeting the parson in the rectory, depending on your religious background. But once you settle into Unit 14, soak in the sun from the bow windows and lose yourself in the views of the Esplanade and the Charles River, you may forget you're living where a church actually stood, save for the silence of the sanctuary...