St James' Cathedral Old Rīga

Built in 1225, this church has ping-ponged many times between Catholic and Protestant, and has been home to many languages and communities, including Germans, Swedes, Poles and Estonians. Most notably, it was here that Latvians first heard a mass in their own tongue during its Lutheran stint in 1523. Exactly 400 years later it was handed back to the Catholics to be used as their cathedral.