Cathedral of the Holy Trinity, Blaj

The Cathedral of the Holy Trinity (Catedrala Sfânta Treime) in Blaj, Romania is a Romanian Greek Catholic cathedral commissioned by bishop Inocențiu Micu-Klein in 1738. The church was built by Viennese architects Anton Erhard Martinelli and Johann Baptist Martinelli, being completed in 1749.

The building was extended in 1838, when the two monumental towers were added.