Stadiums as of Jan 1, 2020

Franchise    - Stadium Model - Stadium -  City
Augustus     - Metrodome     -  1/1/18 - 1/1/18
Westmoreland - Jacobs        -  1/1/14 - 1/1/14
Pittsburgh   - Jacobs        -  1/1/08 - 1/1/08
Norfolk      - Metrodome     -  1/1/07 - 1/1/06
Snake River  - Shea          -  1/1/20 - 1/1/20
Alaska       - Skydome       -  1/1/07 - 1/1/06
Harbor       - Atlanta       -  1/1/07 - 1/1/06
Mexico City  - Metrodome     -  1/1/06 - 1/1/06
Honolulu     - Miami         -  1/1/18 - 1/1/18
Seattle      - Jacobs        -  1/1/14 - 1/1/06
Calgary      - Jack Murphy   -  1/1/17 - 1/1/17
St. Kizer    - Coors         -  1/1/18 - 1/1/18
Detroit      - Shea          -  1/1/06 - 1/1/06
San Juan     - Arlington     -  1/1/20 - 1/1/20

Barcelona    - Atlanta       -  1/1/20 - 1/1/06
Liverpool    - Arlington     -  1/1/16 - 1/1/16
Edinburgh    - Oakland       -  1/1/06 - 1/1/06
London       - Candlestick   -  1/1/06 - 1/1/06
Paris        - Wrigley       -  1/1/06 - 1/1/06
Alexandria   - Oakland       -  1/1/07 - 1/1/07
Amsterdam    - Jacobs        -  1/1/06 - 1/1/06
Morocco      - Jacobs        -  1/1/17 - 1/1/06
Rome         - Briggs        -  1/1/06 - 1/1/06
Stockholm    - Briggs        -  1/1/07 - 1/1/06
Helsinki     - Coors         -  1/1/07 - 1/1/16
Siberia      - Candlestick   -  1/1/16 - 1/1/16
China        - Anaheim       -  1/1/07 - 1/1/06
Melbourne    - Jack Murphy   -  1/1/07 - 1/1/07
 

Stadium: 7 years.
Can change before then (AFTER 5 YEARS), but it costs a first-round draft pick.
New owners, of course, can change their stadium at the beginning of their first full season.

City: 15 years.
Can change after 10 -- costs a 2nd and 3rd round pick (no first-rounder)
Can change after 7 --  costs a first round pick
If a new owner wants to change their city:
A) Must be approved by the League President FIRST then sent to the Commissioner for approval
B) Must have a reason to do it. "I don't like the altitude of my city" Isn't a good enough reason.
C) Must be at the start of a new season. No mid-season changes