The "Hospital Chapel on the Martinsberge" is a flat-roofed sacred building with a semicircular choir and bell tower.

The three-aisled ashlar building dates back to the 12th century. Many details point to the Romanesque era. The former side aisles and hospital buildings have not survived.

The choir space is illuminated by a rectangular window on the north and south sides. The choir area, which has been raised by 48 cm with three steps, is separated from the rectangular church space by a triumphal arch. The church space is approximately 11.5 meters long and 7 meters wide, featuring three Romanesque clerestory windows on each side and two on the west wall.

A Baroque reconstruction may have taken place around 1708, as there exists a papal indulgence document from that year. In 1854, the chapel was left to decay, with only wall remnants remaining by 1890. The bell tower was only added during a roof renovation in 1898. The Holy Spirit Chapel is first mentioned in a letter of indulgence from 1332, issued in Avignon, now kept in the city archive of Lahnstein. According to documentary evidence, a vicarage was already in place before 1342. In 1505, a court near the Holy Spirit Chapel (not the hospital) was sold. The court near the Holy Spirit Chapel is also mentioned in 1575.

The chapel is located by a freshwater spring, which was said to have healing properties as early as the 14th century, and along the old high road from Oberlahnstein to the Erzbachtal (mining since Roman times), Bad Ems, and Nassau.

Christian von Stramberg reports on the legend of the wealthy Regina Waibelung, who founded a leper hospital due to heartache and also cared for the sick there herself. When she fell ill herself, a spring appeared after a prayer, and she recovered after washing her hands in it. The healing spring was restored in 1972 with a natural granite basin and commemorative plaque, and revamped in 2018.                                                                                                                             The last interior renovation took place in 2000 by the "Support Association for the Preservation and Renovation of the Catholic Churches and Chapels of the Parish of St. Martin." Nothing of the chapel's old furnishings has survived.

Today, the chapel is equipped in Baroque style. The altar once stood in the Wenzel Chapel. Two altar paintings date from 1816 and previously hung in the parish church of St. Martin. The figures of saints Wendelinus, King David, and Sebastian are also Baroque, while the neo-Gothic Madonna is a copy of the Hallgarten Madonna crafted by Caspar Weis.

Once, a Stations of the Cross led up to the Holy Spirit Chapel, which was walked during Holy Week and is now commemorated by the street name "Auf’m Charweg." Older citizens can still remember the Markus procession (April 25) and the prayer processions held in the three days before Ascension Day, which concluded with a Holy Mass in the Holy Spirit Chapel.