The old parish church of St. Cyriakus in Niedermendig, a district of Mendig, is a Romanesque church from the 12th century.

From 1852 to 1857, a neo-Gothic church was built on the north side of the old parish church according to plans by the Cologne cathedral master craftsman Vincenz Statz, which was dedicated to St. Cyriacus and St. Barbara was consecrated.
During the renovation work of the old church from 1886 to 1888, medieval wall paintings were discovered, which have been exposed again since 1897.
Based on stylistic comparisons with other churches and dendrochronological studies of the wooden beams of the roof structure, the time of the church of St. Cyriakus is assumed to be around 1180.
Eleven Romanesque frames made of oak, which were felled between 1175 and 1195, are still preserved above the central nave.
Another beam in the western part of the church was dated from 1166 to 1186. During this time the west tower was erected, of which the first two floors were completed in 1216.
The first written mention of the church and the parish comes from the year 1215.
In 1474 the tower was raised by the two upper floors, as confirmed by an inscription on the outer wall, and covered with a pointed helmet.
In the second half of the 15th century a Gothic chapel was added to the choir.
The church suffered damage during the Thirty Years War and in 1620 the tower burned down.
Until 1802 St. Cyriakus was a separate church of the Trier cathedral chapter.

The wall paintings in the old church from the 12th, 13th and 14th centuries are particularly worth seeing.