🔗 The Prague Pneumatic Post system (early mechanical networking)

The Prague pneumatic post (Czech: Pražská potrubní pošta) is the world's last preserved municipal pneumatic post system. It is an underground system of metal tubes under the wider centre of Prague, totaling about 55 kilometres (34 mi) in length. The system started service in 1889 and remained in use by the government, banks and the media until it was rendered inoperative by the August 2002 European floods.

Sold on by former owner Telefónica O2 Czech Republic after some limited attempts to make repairs, the system now belongs to businessman Zdeněk Dražil, who has announced plans to repair and reopen it as a working tourist attraction. As of 2012, however, it remains closed.