The Cathedral of St. John the Evangelist, also known simply as St. John’s Cathedral, is a Catholic cathedral in Boise, Idaho, United States. It is the seat of the Diocese of Boise, and is listed on the National Register of Historic Places. St. John’s Cathedral was designed by one of the first architectural firms to work in Boise, Tourtellotte and Hummel. Built in the Romanesque Revival style, it was modeled after the Cathedral of Mainz in western Germany.
The exterior is Boise Sandstone, quarried just above the city at Table Rock. The building is cruciform in shape and measures 170 feet (52 m) from front to back, 95 feet (29 m) at the transepts and 65 feet (20 m) in the nave. The building was designed to have two towers topped with spires flanking the main façade, but they have not been completed. A rose window graces the front of the church and the center gable above the main entrance features a statue of St. John the Evangelist on its peak. Corbeling, a continuous band of small projecting arches, encircles the building at the roofline.
The stained glass windows in the nave depict scenes from the life of Christ. The large widow in the north transept depicts the Adoration of the Magi, flanked by widows portraying St. Alphonsus Ligouri and St. Theresa of Avila. The south transept window depicts the Ascension and is flanked by windows portraying St. Patrick and St. Rita. The windows in the sanctuary depict St. Joseph on the north and the Blessed Virgin Mary on the south. In the apse are windows portraying the Sacred Heart of Jesus and the Immaculate Heart of Mary. They are flanked by windows portraying the Four Evangelists. The windows were installed in 1920, except the window portraying the Holy Spirit in the center of the apse, which was installed in 1979. St. Cecilia is depicted in the window above the pipe organ.