Back in the 13th century, a small roman Basilica to the Holy Ghost, which was probably destroyed in a fire in the 14th century, stood where you now have the Church of the Holy Ghost.
An early Gothic church was built in place of the basilica and it was where the opening mass to commemorate the founding of Heidelberg University was held on 18th October, 1386. Under Rupert III, the choir stall of the church was pulled down and replaced with a larger one. The hall chancel was completed in 1410, the long house and the construction below the tower in 1441. Ludwig III laid the foundation for the later famous Palatinate Library, the BIBLIOTECA PALATINA, where the first books of the construction of the Church of the Holy Ghost were displayed. During the reign of Ludwig V (1508-1544), the tower was built and completed. During the Reformation, the Church changed multiple times between a Lutheran and Reformist-Calvinist confession. The reformed Heidelberg catechism was created in 1563. With the Thirty Years War and Heidelberg being conquered by Catholic troops, the city and the Church were Catholic and Pope Gregor XV had the BIBLIOTECA PALATINA brought to Rome in 1623 as spoils of war. In 1693, the Church was severely damaged in the course of the Palatinate-Orleans War. Almost all the tombstones of the Prince Electors of the Palatinate region were destroyed, except for that of Price Elector Ruprecht II. From the 5000 books and 3524 manuscripts, only 1816 and 885 respectively made it back to Heidelberg; the rest remained in the Vatican. Over the next two hundred years, both Catholics and Protestants made an equal claim to the Church; therefore a diving wall was built and the Catholic mass was held in the hall chancel, while the evangelical service was held in the long house. It was only in 1936 that a compromised was reached with the Catholic Church and this Church was handed over to the Protestant Church in Baden. On the occasion of the Feast of St. John in 1936, the evangelical Holy Ghost Parish was finally able to hold mass in a church without a dividing wall.