This a picture called
"La foire du Lendit" Pontifical de Sens, France, 14th century
BnF Ms. Latin 962, fol. 264
Source: Medieval Trade and Travel: Home
And can be dated with additional detail to found here.
That image is at the source here, at the Bibliothèque nationale de France:
La foire du Lendit
Pontifical de Sens, France, XIVe siècle
Paris, BnF, département des Manuscrits, Latin 962, fol. 264 //
La Bénédiction du Lendit. Miniature du manuscrit latin Pontificale Senonense, édité entre 1301 et 1400. – Pontifical de Sens, XIVème siècle, latin 262, F. 264r Bénédiction du Lendit. – Source : Gallica, Bibliothèque nationale de France, Département des manuscrits, Latin 962, domaine public.
Source l'enfance en moyen age, BNF and Bénédiction de la Foire du lendit
A "Foire du Lendit" means that this is around St Denis in France and we see a bishop of Paris blessing a trade show, a fair or market.
The fair of Lendit (or fair of the Landit), opened for two weeks every 11 of June, day of Saint Barnabé, until June 24, day of the Saint-Jean, with the plain Saint-Denis, between Paris and Saint-Denis. It was from the 9th to the 16th century one of the most important fairs in France and the largest in the Île-de-France. It attracted a thousand merchants from all over Europe and Byzantium… It sold the parchment used by the University of Paris and its students.
In 1411, appears the last mention of the Perron in a "List of the price of lodges at the fair of Lendit" written under the abbey of Philippe de Villette. The Perron was a prominent stone on which one could stand or sit, located near the Montjoie, tumulus located on the way to the Estrée . The Montjoie and his Perron served as a platform and a pulpit to be preached during the fairs: every year, the bishop of Paris came to bless the fair of Lendit in June. These are the Montjoie and the Perron which must be recognized under the veiled terms used by the Pontifical of the Church of Paris concerning the ceremonial of the blessing of the fairs: the most eminent place where the bishop settled with the procession, which required a rather large platform, was the Montjoie, while the highest place, a kind of platform for the sermon, was the Perron. A place told to the cadastre, a street, an impasse testify to the intensity of the memory of the Perron.
As this is from a book and looks like this in context:
(click to enlarge)
As seen in the French Wikipedia entry, the structure in the middle with the clerics on top seems to be "Montjoie and Perron" (Anne Lombard-Jourdan: "Montjoie et Saint-Denis! Le centre de la Gaule aux origines de Paris et de Saint-Denis", Presses du CNRS: Paris, 1989, p392.), a special elevated structure for that purpose. Later a Montjoies would be depicted in this way:
or like here:
While the depiction of the "building" may include a certain artistic licence, the disinterest of the people going about their business at that late medieval time is perhaps not.