Which London Underground line opened first?

Related questions

1. How deep is Metro St Petersburg?
2. How much is a 7 day unlimited MetroCard?
3. Which London Tube line has the most stations?
4. Why is the Bakerloo line called that?
5. How fast does the central line go?
6. What is Nol Card Dubai?
7. Is the Metro free?
8. What are the Dubai Metro timings?
9. Can you drink tap water Russia?
10. What time Metro opens?

Tags

1. #world
2. #railway
3. #first
4. #street
5. #opened
6. #william
7. #underground
8. #stockwell
9. #thames
10. #december
11. #under
12. #electric
13. #river
14. #london