I was intrigued when this memorial was pointed out by our Guide on our way to St Stephens Square and even more intrigued when I researched its history and iconography. I hadn't seen or heard of such a memorial before but I now know there are others elsewhere in Europe. What follows is a precis of the Wikipedia entry for this column.
The Plague Column or Trinity Column is a Holy Trinity Column (Marian columns are religious monuments depicting Virgin Mary on the top, often built in thanksgiving for the ending of a plague (plague columns) or for some other reason. The purpose of the Holy Trinity columns was usually simply to celebrate the church and the faith, though the plague motif could sometimes play its role in their erection as well) located on the Graben, a street in the inner city of Vienna. Erected after the Great Plague epidemic in 1679, this Baroque memorial is one of the best known and most prominent sculptural artworks in Vienna.
Fleeing the city, the Habsburg emperor Leopold I vowed to erect a mercy column if the epidemic would end. In the same year, a provisional wooden column made by Johann Frühwirth was inaugurated, showing the Holy Trinity on a Corinthian column together with nine sculpted angels (for the Nine Choirs of Angels). After many amendments to the design and the involvement of several sculptors, the column was inaugurated in 1694.
The following is a straight take from Wikipedia on the iconography of the column:
https://en.wikipedia.org/wiki/Plague_Column,_Vienna
The column has a complex iconography, the basic message of which is that the plague and the Ottomans' Second Siege of Vienna (1683), both of them punishments for sin, were averted or defeated by the piety and intercession of the Emperor Leopold I. (The pillar thus also represents a (victory) monument to that emperor.)
In the iconography, the Trinity expresses itself several times in the number three, namely vertically in three stages:[3]
- the pedestal, reserved for mankind, in the upper third of which Leopold I prays to God as an intercessor;
- a second, higher level occupied by angels, in an intermediate zone between God and mankind;
- and the highest level, reserved for the Holy Trinity.
In addition, there is also a tripartite division in plan, which establishes a connection between the sacral program and the three parts of the Habsburg monarchy:
- The western face is dedicated to God the Father and bears a double-headed eagle, the coat of arms of the Holy Roman Empire, as well as the coats of arms of the Inner Austrian lands, the duchies of Styria, Carinthia and Carniola. Between the western and eastern wings are the coats of arms for the core countries of the monarchy.
- The eastern face is associated with the Son of God and bears the coats of arms of the kingdoms of Hungary, Croatia and Dalmatia, as well as Bosnia.
- The northern face, which belongs to the Holy Spirit, is decorated with the coats of arms of the Kingdom of Bohemia, the Margraviate of Upper Lusatia and Lower Silesia, as well as the Duchy of Silesia.
Again indulging myself here but I hope you find it interesting too.