Stuttgart 21 is railway project around Stuttgart main station which costs nearly 10 billion euro at this point. It converts the current terminus station into an underground station. The latest estimate for start of operation I found is December 2025 (initially 2019).

For this question, we define "start of operation" when they made an official announcement, a train stops at the underground station, passengers board or exit, and then the train departs to the other side (not a terminus station). Test runs do not count.

Resolves YES immediately if the start of operation happens.

Resolves NO on 2026-01-01.