Holy Trinity Cathedral

Holy Trinity Orthodox Cathedral is the Cathedral Church of the Orthodox Church in America Diocese of the Midwest. It is one of only two churches designed by Louis Sullivan, one of the seminal architects of the late 19th and early 20th centuries. It is listed on the US National Register of Historic Places and is designated a Chicago Landmark.

The church was commissioned by the growing Russian congregation of Chicago, Illinois, and stands within the neighborhood known today as Ukrainian Village. It remains one of only two Orthodox Churches servicing the Orthodox-Christian community in Ukrainian Village. Construction work, partly financed by a personal donation of $4,000 from Tsar St. Nicholas II of Russia, lasted from 1899 to 1903.

The church retains many features of Russian provincial architecture, including an octagonal dome and a frontal belltower. It is believed that the emigrants wished the church to be "remindful of the small, intimate, rural buildings they left behind in the Old World". Archival references point to a small wooden church in the Siberian village of Tatarskaya as a particular inspiration for the final design. To this traditional Russian basis of the overall design, Sullivan added decorative elements more characteristic of his own larger corpus of work, influenced by the Art Nouveau and Arts and Crafts movements, as seen, for example, in the abstract decorative design over the western entrance to the church.