[2] On 13 March 1782, the parish purchased the farm buildings of the former Royal Monastery for 23,900 guilders to construct a Tolerance Prayer House with a rectory.

[3] Gottlieb Nigelli, a sub-architect in the Court Building Office and protégé of State Chancellor Wenzel Kaunitz, was assigned the task of planning the Reformed House of Prayer.

As a result, architect Gottlieb Nigelli designed the street façade to resemble a simple residential building, with the two main portals concealed within an inner courtyard not visible from the alley.

[3] The industrialist and banker Johann von Fries, who made the largest financial contribution to the construction of the prayer house,[6] simultaneously commissioned the Palais Fries-Pallavicini on another plot of the former royal monastery.

The neoclassical palace was designed by Johann Ferdinand Hetzendorf von Hohenberg, Nigelli's superior in the Court Building Office.

The Fries-Pallavicini Palace faced criticism for the unusual proportions of its exterior and the elaborate caryatids by Franz Anton von Zauner at the main portal.

"[7] In contrast, the Reformed House of Prayer faced the challenge of "drawing the line between extravagant splendor and raw simplicity; and woe betide the architect who is not philosopher enough before he picks up the tools.

"[8] An anonymous author, presumably Nigelli, responded to these critiques, likely receiving a reply from Hohenberg, accusing him of being "Vienna's Trasyllus,"[9] referencing the ancient philosopher who compromised his integrity through his relationship with Emperor Tiberius.

In response, court architect Johann Amann obtained permission in 1815 for a structural modification that complied with the Tolerance Patent restrictions.

He created an entrance in the side façade of the prayer house, leading into an intermediate passageway that was designated as not part of the actual sacred space.

After years of deliberation, the leadership of the congregation decided in 1885 to redesign the building, which included changes to the external appearance and adaptations to the rectory to meet contemporary living requirements.

A new organ loft was constructed above the main portal in the original apse, and the existing right-side gallery was extended, increasing the total seating capacity to 205.

All sanitary facilities, as well as gas, water, and electricity pipes, doors, windows, floors, and the heating system, were completely renewed.

[30] This market commemorates her introduction of the Christmas tree decorated with candles in Vienna in 1816, a tradition she brought from her home in Nassau-Weilburg.

The blind court organist Josef Labor gave several concerts there from 1905 to 1907, and in the 1930s, the Vienna State Opera, the Wiener Männergesang-Verein, and mezzo-soprano Rosette Anday performed in the church.

[31] During the 2006 renovations, efforts were made to improve the church's suitability for concerts, including the installation of a sound system, enhanced lighting, and castors for the communion table.

Notable pastors who have served in this capacity include Carl Wilhelm Hilchenbach, Justus Hausknecht, Gottfried Franz, Friedrich Otto Schack, Gustav Zwernemann, Johann Karl Egli, and Peter Karner, many of whom also held the position of (provincial) superintendents in the Protestant Church of H.B.

The complex consists of the church building and the adjacent vicarage to the south, connected by two side wings that enclose a trapezoidal inner courtyard.

On the outer wall facing the inner courtyard, two former main entrances, framed by Tuscan half-columns and a straight entablature, can be found.

[19] Above these former main entrances is a circular memorial plaque dedicated to Emperor Joseph II, with Latin text based on a design by Göttinger Professor Christian Gottlob Heyne.

In front of the main room on the long side facing Stallburggasse is a corridor, at the end of which a spiral staircase leads to the galleries.

[19] Following the 1887 renovation, these side entrances were intended to allow separate access to the church for men and women, reserving the inner main portal for high feast days, blessings, and funerals.

The interior of the church is characterized by a lack of images and crosses, reflecting a strict adherence to the Second Commandment in the Reformed tradition.

[39] Three wall inscriptions in gold lettering, donated by the Wittgenstein family in 1889, feature biblical quotations: "Thy kingdom come" is positioned above the pulpit, while the undersides of the side galleries display "All that breathes praise the Lord, hallelujah!

The oldest plaque, dated 1822, honors Pastor Carl Wilhelm Hilchenbach, described as "the faithful promoter of this building, the pious leader of our souls, the teacher of our youth, the father of our poor."

A marble plaque from 1925 honors the parishioners who died in World War I and contains an exhortation to peace, with its text written by theology professor Josef Bohatec.

[17] The most recent memorial plaque dates from 2005 and names Zsigmond Varga and Ernst and Gisela Pollack as representatives of the church members murdered in the concentration camps of the National Socialists.

[24] The semi-circular, early classicist pulpit dates from 1774 and stands on Tuscan columns and pilasters made of reddish marble, adorned with gilded acanthus ornaments.

The newly acquired communion tableware, made of fire-gilt silver, is hallmarked with the year 1807 and consists of a wine jug, two goblets, and a bread plate.

[42] The Jahn organ, which was last renovated in 1929, could not be fundamentally repaired after the Second World War due to a lack of funds, ultimately falling into a desolate condition.