Prague’s pneumatic post: how the city once sent mail by air

Say Prague and you picture fairytale castles, winding medieval lanes, and that famous clock. What few realize is that beneath those streets lies a genuine postal network of tubes built back in the 19th century: pneumatic post. In Prague, letters once traveled literally on air, racing through pipes in sealed capsules—a very real service that operated for more than a hundred years.

What is it, exactly?

Prague’s pneumatic post was a web of tubes that used compressed air to send small capsules carrying letters and documents. It opened in 1889 and offered remarkable speed: a message could cross the city in just a few minutes.

How it worked

Engineers laid about 55 kilometers of metal pipes beneath the streets, each roughly the diameter of a plastic bottle. Inside, compact carriers weighing up to three kilograms shot along the lines, driven by air—much like a gust through a straw. The network linked post offices, workplaces, banks, and ministries; pipes even crossed the Vltava via bridges. With 24 stations, the system ran with impressive reliability.

Historic moments

During the Second World War, the pneumatic post helped move urgent messages. In May 1945, as fighting raged for Prague, information was sent through the system to the besieged Radio building. In peacetime, the network hit its stride in the 1970s, carrying up to a million messages a month. It was seen as both practical and, in its way, prestigious.

What went wrong

In 2002, severe flooding struck Prague. Water inundated the machinery that supplied air to the network, forcing the service to shut down. It was never restarted.

Could it come back?

In 2011, Czech entrepreneur Zdeněk Dražil bought the entire system. His aim was to restore at least part of it and turn it into a tourist attraction. The estimate hovered around 5 million Czech crowns—about 200,000 euros. The plan was straightforward: repair one line, show visitors how it all worked, and even launch capsules again. As of 2021, though, restoration had not begun, and there have been no updates since.

Where things stand

Today, the pipes still lie beneath Prague. They’re out of service, yet not dismantled—a paused past the city keeps underground. If the system is ever revived, it would offer a rare chance to see, firsthand, what once passed for the mail of the future. For now, pneumatic post remains one of the most unusual forgotten technologies, quietly waiting for a second act—if fortune allows.