I have seen many European stadiums including some iconic venues in Barcelona, Brussels, Dortmund, Madrid, Manchester, Marseille, Paris and Rome. My wishlist for the future is stated below with the stadiums in Milan and Valencia on top since they will be demolished in the near future:

1. Estadio Mestalla - Valencia (Valencia CF)
2. San Siro - Milano (AC/Inter Milan)
3. La Bombonera - Buenos Aires (Boca Juniors)
4. Anfield Road - Liverpool (Liverpool FC)
5. Celtic Park - Glasgow (Celtic FC)
6. Allianz Arena - München (FC Bayern München)
7. Sükru Saracoglu Spor Kompleksi - Istanbul (Fenerbahce)
8. Fritz Walter Stadion - Kaiserslautern (1.FC Kaiserslautern)
9. Saint James' Park - Newcastle (Newcastle United)
10. Craven Cottage - London (Fulham FC)

Furthermore I would like to see all Eredivisie stadiums in my country. There are still a few missing, mainly in the north (Groningen, Leeuwarden, The Hague, Zwolle).