The history of Masná street stretches back to the Middle Ages, when it was called Masotržní or Masný trh (meat market), at the time naturally in German as Fleischmarkt. Since ancient times there had been meat shops here (macella). Old Town butchers (carnifices) had a privilegium from the kings Jan and Karel IV, which then burnt down and was subsequently renewed in 1417 by Václav IV. They had their own guild and order here from 1359. Each shop paid one hřivna to the royal chamber.
Practically every building in this ancient street in the very heart of the Old Town had its house sign and eventful fates associated with its owners.
Prakticky každý dům v této starodávné uličce v samém srdci Starého Města měl své domovní znamení, za nímž stály pohnuté osudy jejich majitelů.
The genealogy of the corner building number 702/9, in which Hotel Mysterius Carnival is now found, stretches back to the 14th century. In the year 1400 its owner was a koster, or wine taster, by the name of Walter, which in those days was called a "gustator vini". This function was usually held by municipal officials, who evaluated a sample of wine taken from a keg before tapping. From 1438 the building was adorned with the house sign and picture of St Jerome, then from 1653 with the sign At the Three Chimneys and in 1725-1897 At the Black Lamb. In 1445 the building was purchased by Zikmund, the son of Jan Bradatý and in 1563 the building passed to Pavel Sedlčanský of Kosmačov.
In the modern era, Masná went down in history as a place of unbridled merry-making, masquerades and carnivals. Of particular renown was the building U Vusinů with its two "very gorgeous halls" where its owner, the Mayor of Prague of the time, Jan Václav Friedrich of Friedberk, organised masquerades or "balls in mummery or masks" two or three times a week. Masquerade balls developed in the Romance countries and its roots stretch back to Ancient Greece. They were held to honour the god of the vine and unbridled merry-making Dionysus. The Ancient Romans adapted their custom, but their god was named Bacchus. Masters and slaves traditionally switched roles.
In Austria masquerades were permitted on 29 December 1751, but only for the upper classes, "whosoever has acquired the proper degree of nobility, and has been of righteous morals and good repute, without engaging in simple civil trades." This did not apply however U Vusinů, where everyone could feel free to choose whatever disguise they wished. This is why these carnivals enjoyed great popularity.
To však neplatilo U Vusinů, kde se každý mohl cítit svobodně a zvolit přestrojení, jaké chtěl. Proto se karnevaly těšily velké oblibě.
Even the lower classes could become noblemen and vice versa.
Carnivals U Vusinů (in Czech called masopust) always lasted from 6 in the evening until 2 in the morning.
The originally Gothic, Medieval, Imperial and Art Nouveau buildings on Masná were gradually torn down and replaced with buildings of all kinds of styles. Some underwent Baroque reconstruction in the 17th century and the 1730s, such as the home at number 620 At the Golden Swan (originally U Vusinů) or in the Neo-Renaissance style such as the building of the Old Town Girls' School at 700 and 701. Also significant are the functionalist buildings at 703 and 702, built in 1929-1930. One of them was designed by the prominent Prague architect Olřich Tyl for the violin-maker Otakar Špidlen. The local school on Masná street was even attended by Franz Kafka (1883-1924).
Masná street today is thus a microcosm of various architectural styles, just like all of Prague. Rightly it is included in the UNESCO heritage site.