I've recently started watching a YouTube channel with a lot of Stronghold content. Surprisingly -- since I've never enjoyed the genre in the past -- I've loved the videos. So, with no experience in the genre, what are some of your favorite castle / city builders (with defense)?

Well, I like Tropico 4, but the defense part is a very small one. I`m more of a peacefull builder than a warlord. :-D

Do Terraria and Craft the World count?

If not, I'll go with ANY of the Settlers games.

I swear the more I browse this board, the more I see people who would give similar responses that I would give.

Well only less verbose than me, thats for sure :D!

EDIT: Or perhaps not. Come to think of it I immediately thought of Anno right after The Settlers half a second before I gazed at your comment. But yeah, those games are the mad notes.

Yeah, Tropico looks interesting but I'm looking more medieval fantasy or historical. Will check out Settlers! Anno? Hmmmm... will take a look!

Maybe Cultures?

https://www.gog.com/game/cultures_12

https://www.gog.com/game/cultures_34

CivCity Rome

https://www.gog.com/game/civcity_rome

Imperium Romanum (has a bit more military scenario's then CivCity Rome, though here as well the military aspect is quite basic): at the moment on sale for €1,50: https://www.gamersgate.com/DD-IRG-STEAM/imperium-romanum-gold. The download got removed though, it's just a Steam key for sale now.

For those who want it on GOG (other Kalypso games are here, why not this one?) put your vote here:
https://www.gog.com/wishlist/games/imperium_romanum

I've been playing Banished lately. I've not played many city builders to compare it to but I've been enjoying it.

Settlers II
Simcity 2000
Afterlife

Anno 1404
Dwarf Fortress
Startopia
Settlers 2
Pharoah

Anno 1404 Venice, Patrician Rise of Dynasty.

Simcity Societies, my favorite game in the SimCity series.

Pharaoh, definitely Pharaoh. Bulding massive monuments while still maintaining a problematic city (fire, starvation, enemies, lack of funds...) is one of the best fun I have ever had while playing games.

Caesar II...so many memories with this one. I like the rest of the Caesar series, as well as the related games Pharaoh and Cleopatra, Zeus and Poseidon, and Emperor.

Well, I'm going completelly of the charts now but older Bullfrog games do some "city" building with a lot of defense as well. Dungeon keeper, Populous 3 an Black and White (if you can manage to get a copy) are a very entertaining and fun way to build cities. Except when you get a vulacano in the center of yours!