What are the pros and cons of having an open field fortress vs an in-mountain excavated one?

//ads -- adsterra.com -- native banner
?>
I've been playing Dwarf Fortress for a long time now but I never know how to decide if building a fortress out in the open is worth the higher resource cost.
What are the pros and cons of each method?
Pictures about "What are the pros and cons of having an open field fortress vs an in-mountain excavated one?"



Absolutely NEVER Buy This Type Of Land
Sources: Stack Exchange - This article follows the attribution requirements of Stack Exchange and is licensed under CC BY-SA 3.0.
Images: Angie, Lukas, Sohel Patel, Karolina Grabowska