It can be done, but geology under Prague is terrible. A lot of broken layers with lots of sediments and water.

Our subway system was rather expensive to build and maintain, doing this with trains would probably be too expensive even for a fairly rich city like Prague.

There are some rudimentary plans for railway tunnels under the very center of the city, but the expected cost is eye-watering.

Tap into the limitless cornucopia of the EU. For protecting the historic scenery, cultural heritage, being good for the environment, enabling shorter travel times, supporting tourism, intercultural exchange...

We're in a phase of low interest rates, resulting in easy money politics. Burn some billions before others do ;->