Diaphragm Arch Interesting Architecture in Mala Strana

You have probably never heard of a diaphragm arch. Yet you have seen such arches many times on your wanderings in Prague. The Czech translation is prampouch and you occasionally come across this word in an article about Prague on the internet or in a guide book under the heading architecture in Prague.

What is a Diaphragm Arch?

Diaphragm arches are supporting arches between two houses which do not share the same wall. These arches span a narrow passage and ensure the stability of the neighbouring house. These arches are often clad with roof tiles to protect against rain because water can damage their sturdiness. In the Middle Ages, the houses in Mala Strana were built of wood, the narrow alleys between two adjacent buildings ensured that a fire could not easily spread to the house next door.

Where do you find Diaphragm Arches

These arches can be found in several places in the Mala Strana district, which is not surprising because Mala Strana is the oldest part of Prague and there are still many houses of medieval origin. Their cellars are often original but the houses themselves were usually rebuilt and added to in later periods.

1. Between St Thomas Church and Oettingenský Palác
The Letenska street connects Malostranska metro station with Malostranské namesti. Take tram 22 and just before you reach Malostranské namesti, the tram runs through a narrow alley between the Oettingen Palace and St Thomas Church. This stretch is single track. When you go on foot, you walk through an indoor covered passage which is part of the palace. Take a good look at the tram track next to it, look up and you will see diaphragm arches.

Oettingenský palác was originally a medieval building, which is evident from the Gothic cellars. Like so many houses in Mala Strana, it was rebuilt in the sixteenth century, preserving the cellars. The current building dates from the early eighteenth century.

In 1927, a pedestrian passage was added in the northern part of the palace and in 1948 this became an underpass for cars. There is an underpass for pedestrians where they entrance portal used to be.

2. Thunovská Street
The connecting arches in Thunovska Street are not built for decoration. As the population of Mala Strana increased in the Middle Ages, more living space was needed and existing houses were enlarged. The houses in Mala Strana had no foundations but were built on the sand of the banks of the Vltava River. The connecting arches made the houses so stable that many are still standing today.
Thunovská Street runs under the Castle Stairs that give access to Prague Castle. The connecting arches are in the upper part of the street.
The street is named after the Thun-Hohenstein family (Thun-Hohenštejnové) who lived in the Thun Palace (Thunovský Palác), now the Embassy of the United Kingdom.

3. U Lužického Semináře Street
The alley between numbers 24 and 26 in U Lužického semináře Street is a good example of a medieval firebreak with connecting arches.
This alley is recommended in all guidebooks and sites about Prague as ‘the narrowest street’ in Prague. The owner of the Certovka Vinarna, the Devils Vinotheek, has taken it a step further by installing working traffic lights at the entrance of the alley. A guaranteed success because tourists come in droves to see this attraction and many go in to drink a glass of wine.

4. Old Town Square / Melantrichova
Opposite the astronomical clock and next to the Erpet shop selling Bohemian glassware is a narrow passage to Melantrichova Street. The two buildings on the square are connected by a supporting arch with a small roof with tiles.