Mission São João Batista, Archaeological site in Rio Grande do Sul, Brazil.

Mission São João Batista is an archaeological site at São João Velho in Entre-Ijuís, Rio Grande do Sul, reached via the BR-285. Its ruins include the church, the cemetery and the school, plus workshops, a dam and old roads. Carved sandstone pieces lie across the grounds, and interpretive panels quote letters written by the priests.

The reduction of São João Batista was founded in 1697 by Father Antonio Sepp, after the village of São Miguel Arcanjo was divided due to population growth and supply difficulties. Sepp arrived with 2,832 people from São Miguel. Work on the church began in 1708, when 3,400 people lived in the settlement. Sepp, skilled in music, architecture, clockmaking and metallurgy, extracted iron from itacurú stone to cast bells and built a clock whose dial displayed the Twelve Apostles.

The site shows how Jesuit missionaries and Guarani people lived and worked together through building styles and everyday objects left behind. Recovered items tell the story of shared daily activities and interactions at this place.

The site is located between Santo Ângelo and São Miguel das Missões with regular visiting hours for guests. The grounds feature interpretive signs that help explain the excavated structures and their purposes.

Excavations have revealed patterns of colonial life through a variety of objects recovered from the 17th century. These findings show details about crafts, food, and technical skills of people who lived at this location long ago.