The Basilica of Our Lady Immaculate is Guelph's defining landmark: a massive Gothic Revival church built in grey local limestone that sits high above the city centre on a hill, its twin towers visible from most of the city. Construction began in 1876 and continued for decades; the basilica was completed in stages and is still being embellished. The interior is spacious and detailed, with good stained glass and the solemn atmosphere of a building that was meant to impress.
The basilica was designed by Joseph Connolly, one of the leading Gothic Revival architects in 19th-century Canada, who modelled it loosely on the Cologne Cathedral. It was designated a minor basilica in 2014, one of only a few in Ontario. The hill setting, accessible via a broad flight of steps from the lower town, gives it a theatrical presence that the interior more than lives up to.