São Miguel das Missões (literally "St. Michael of the Missions", pronounced SOW (like the female pig) mee-GHEL DAHS mee-SOYS) is a city built around the historic St. Michael Archangel Archaeological Site which contains one of the historic ruins built by Portuguese Jesuits and Tupi-Guarani indians. It is one of the most famous missions from the time of the Guarani Jesuit Missions in the new world.

The site, commonly called the ruins of St. Michael of the Missions, is a UNESCO World Hertigage site. The main building of the mission, the central church, was erected in the 18th century between 1735 and 1745.

The site is also part of the International Iguassu Missions Route and is visited by tourists from all over the world. A special light show shown each night explains, in Portuguese, the turbulent history of the mission. The Mission's history and a recreation of the Mission are featured in the 1984 American film "The Mission."