The birthplace of Onkel Hayn lies on what was known during the time of the Holy Roman Empire as the “Krönungsweg” – the most direct path between the cathedral and the town square, or in other words between coronation and festivities. No fewer than 10 emperors took this path, making it one of the most important streets in the empire. This attracted the rich business owners and as a result, the street became known simply as “Markt”, and most of the buildings had a store front on the ground floor. The Grüne Linde, where Onkel Hayn lived, was Markt 13, and faced the Hühnermarkt, a small square that had once been the site of a church cemetery. As Onkel Hayn describes it:
Der Linde gegenüber erweitert sich der Markt zu einem geräumigen freien Platz, dem Hühnermarkt mit dem Freiheitsbrunnen in der Mitte. Der Hühnermarkt war ursprünglich der Friedhof des ältesten Frankfurter Gotteshauses, nämlich der Maria Kapelle, die am Ende der Neugaß an der Stadtmauer stand. In dieser Kapelle gelobte Kaiser Karl der Dicke, ein geborener Frankfurter, im 9. Jahrhundert den Bau der Salvatorkirche die einige Jahrhunderte später durch den Dom ersetzt wurde. Die überflüßig und baufällig gewordene Maria Kapelle verschwand im 13. Jahrhundert und mit ihr auch der Friedhof, deßen Plazt von da an der Hühnermarkt einnahm.
According to Wikipedia, at some point the name “Freydhofsbrunnen” was corrupted to “Freiheitsbrunnen”, and eventually an allegorical statue placed in the middle (a woman holding sword and a hat). This fountain was again replaced, this time with one dedicated to the poet Friedrich Stoltze, at the end of the 19th century. A drawing of the original fountain can be seen in this engraving by Merian
And this drawing shows how it would have looked in the 18th century.
In Onkel Hayn’s day this figure was placed in the middle of the circle.
This photo below from 1903 shows the Hühnermarkt taken from the side where the Grüne Linde stood – the Stoltze fountain is in the lower right corner:
Unfortunately almost all the buildings around the cathedral were levelled during WWII and an ugly monstrosity (the Technisches Rathaus) erected over the entire area in the 1970s (see sketch above which shows a yellow outline of the TR superimposed on the map just above the darker yellow line running between the Dom and the Römerplatz). Thanks to public lobbying and private investors a plan has been developed to restore this part of the Frankfurter Altstadt, and should be finished by 2017.