The Müllheim Martinskirche is the most historically significant building in the city. The St. Martin's Church does not unfold the sumptuous splendor that is used to it, for example, by late Baroque churches - the St. Martin's Church is more of a quiet beauty that only opens slowly. She has nothing spectacular. She is beautiful in her simplicity, in her clarity, in her straight line. It is beautiful because its proportions are right because space, light and color form a successful unity.It is special that the Martinskirche stands on Roman underground. Excavations showed that there is probably a larger Roman building under the church. This residential building is one of the largest Roman buildings known here on land, the center and center of one of the largest Roman estates in our area. Evidence of a stately decor found in the form of mosaic stones and remnants of wall painting, with which the living rooms were originally equipped. Also for comfort was sufficiently taken care of. A floor and wall heated room was partially exposed in the southwest corner of the church, where the heating was done from the courtyard side. From there, a heating channel leads into a cavity under the floor, through hollow wall tiles smoke and hot air could be pulled off to the top. (Hypocaust-heating). The tower of today's church comes from the 12th century. On the ground floor, which forms the entrance hall of the church, there are valuable 14th century murals depicting the Last Judgment. The church building received its present form in the late Middle Ages, presumably after destruction in the Swiss wars in 1409. The church received at the end of the 16th century, an extensive decoration in the form of a colossal colossal columnar structure and ornamental Fensterrahmung in the style of the German early Baroque. This painting is unique in the entire southwest of Baden. Today, the Martinskirche serves as a concert hall (291 seats) with an unparalleled acoustics.