Caldes de Montbui in Catalan or Caldas de Montbui in Spanish, is a Spanish town and municipality in the comarca of the Vallès Oriental in Catalonia. It is situated in the upper valley of the Caldes river, and the highest point of the municipality is the peak of el Farell at 816 m. It lies about 30 km from Barcelona and it part of its metropolitan area.
The hot springs have been exploited since Roman times, and the remnants of the Roman baths and other Roman buildings can still be seen. The source of la Font del Lleó in the main square emerges at more than 70 °C. The town conserves parts of its medieval fortifications and the Torre de la Presó. The hermitage of la Mare de Déu del Remei dates from the sixteenth century, as does the church of Santa Maria with its baroque entrance. The roman church of Sant Sebastià de Montmajor, in the village of the same name at the extreme north-west of the municipality, is particularly well preserved.
The artist Manolo Hugué lived and worked in Caldes de Montbui, and his house has been converted into a museum displaying both his works and those of other artists.