The most recent archaeological findings (1988-89) indicate that the Alte Nikolaikirche - the oldest and only Protestant church in Frankfurt dating from the Middle Ages,was built in three phases of construction.
Probably a small church with an almost square foundation was built in the 11th/12th centuries. A steeple was added during the middle of the 13th century; and the chancel and sanctuary were enlarged at the end of the century. The discovery of remains from the walls points to a possible existence of a Romanesque church, which may have served as the house of worship for the imperial palace.
The Alte Nikolaikirche on the Römerberg was originally built as a court chapel, whose chaplain was appointed by the King. In the 15th century the church became the center of the city's charitable work. Since the 15th century, the Nikolaikirche has been widely known as a chapel tot the City Council, being located directly across to the City Hall (Römer).
At one time in the church's history (following the middle of the 15th century), a watchman resided in the church steeple. His job was to announce the arrival and departure of ships on the Main River. With the onset of the Reformation, the church was closed and used as a warehouse.
At the beginning of the 18th century, though, the church was restored and in 1721 reopened for worship. During the following century, the Alte Nikolaikirche served as a garrison church and as a "secondary" church for other congregations in Frankfurt. The church was closed again in 1813 and once more made into a warehouse.
After a needed period of restoration following World War 11, the Alte Nikolaikirche became the "home" of the St. Paul's Congregation (whose "spiritual home" was previously the Paulskirche) in 1949. The church underwent an extensive renovation approximately 20 years ago, during which a basement was built, a new organ was constructed, and a movable altar was designed. The church was reopened in April, 1992 with a Service of Thanksgiving.