You don't have to have a strong religious faith to appreciate the peaceful atmosphere of Tartu Cathedral. Ask when the next mass is scheduled or when you can go for a wander through.
This Old Town Tartu principal church is an ideal place to begin your day of sightseeing. There's lots to enjoy in the vicinity, such as Student's Lock-Up, Tartu Town Hall, and University of Tartu. Take your time at Tartu Cathedral before hitting up these other fine sights.