The jewel of the Oberlahnstein parish church of St. Martin is the organ. 

The most valuable musical instrument was built from 1742 to 1744 by the famous organ builder Johann Michael Stumm in the Hunsrück. The organ builders needet 40 days to install the organ on site. The organ is a work with 22 registers, two manuals and a pedal. It was restored in the 1960s.

The architectural development of the church on the central high street is reflected by four architectural styles: In a 1190s a three-aisled Romanesque basilica was built, the choir of which was extended in 1332 in the Gothic style. The baroque central nave was built in the middle of the 18th century and the side aisles at the end of the 19th century.