13 guest stars who appeared on The Simpsons.

1. Paul McCartney
2. Buzz Aldrin
3. Steven Tyler
4. Stephen King
5. Lisa Kudrow
6. Mel Gibson
7. Tony Bennet
8. Elton John
9. Leonard Nimoy
10. Mickey Rooney
11. James Earl Jones
12. Mark Hamill
13. Kathleen Turner

13 cathedrals in the United Kingdom

1. The Metropolitan Cathedral Church of Christ the King - Liverpool