Osorno's Plaza de Armas is a well-maintained central square surrounded by the city's key civic buildings — the Cathedral of San Mateo, the Municipality building, and a ring of early 20th-century commercial facades. The plaza is the social center of the city in the way that most Chilean plazas are: busy at lunch, quieter in the afternoon, and lively on weekend evenings when families promenade.
The Cathedral of San Mateo (St. Matthew's), facing the square on its eastern side, is a mid-20th century modernist building that replaced an earlier colonial church. The interior is austere but the belfry is visible from across the city. The surrounding streets — particularly Ramírez and Matta — preserve some of the city's best 19th-century commercial architecture, including several wooden German-style buildings with covered sidewalks.