Maybe the Pillar of Skulls and Averburg in Averheim (both would probably give buffs to your units when Averheim is under siege)
The Boatyards of Bechafen, widely considered some of the finest makers of riverboats in the Empire if not the Old World (maybe a boost to trade or more movement range), the sawmills of Bechafen gifted by Karak Kadrin (creates timber resource, lowers building cost maybe)

A harbor of sorts in Dietershafen, it is the primary base for the Imperial Navy (maybe slows seaborne enemies in the area due to being hounded by the navy, or a boost to profit since they are guarded by the navy)

"The River of Echoes" in Wissenland; it's origin point, Kreutzhofen, is not on the map, but maybe it could be a building somewhere else in the province. It is an underground river that connects to provice to Miragliano in Tilea, so it could be built there. Maybe a boost to trade income.

@CommanderSandvich Thanks for suggestions for future additions, perhaps do you have any opinions on the effects of any of the current buildings, as I've been adjusting a couple here and there which I will release once the newest patch drops on the 31st. Also there are a few UI issues I'm working out with as the Waystones of Athel Loren once built has the upgrade symbol over it indicating that it can be upgraded when there is only 1 level of that building, however this is not listed in the province tab that also lists when you're able to upgrade buildings, so it seems just to be a local UI issue

I have taken Bilbali and Tobaro before (as the Empire), but I haven't seen the icon for the landmarks. I guess I have to be a faction other than the empire

Make a Marienburg landmark that gives MASSIVE boosts to trade (either a boost to money from trade or resources produced), it is one of the premier ports in the Old World

Originally posted by CommanderSandvich:

I have taken Bilbali and Tobaro before (as the Empire), but I haven't seen the icon for the landmarks. I guess I have to be a faction other than the empire

You should 100% be able to see them? Hmm are you running other Mods? If they overwrite the templates or superchains they might not show up, but the Empire has 100% has access to the Landmarks and Ports in Estalia

Edit:

NH2486_Deepwatch_of_Tobaro wh_main_bas_brt
NH2486_Deepwatch_of_Tobaro wh_main_bas_dwf
NH2486_Deepwatch_of_Tobaro wh_main_bas_emp
NH2486_Deepwatch_of_Tobaro wh_main_bas_ksl
NH2486_Deepwatch_of_Tobaro wh_main_bas_teb

NH2486_Archecclesiatium_of_Myrmidia wh_main_bas_brt
NH2486_Archecclesiatium_of_Myrmidia wh_main_bas_emp
NH2486_Archecclesiatium_of_Myrmidia wh_main_bas_ksl
NH2486_Archecclesiatium_of_Myrmidia wh_main_bas_teb

These are the faction availabilities for the Landmarks in Estalia and then the Port Landmarks of Bilbali and Magritta are available to all with respect to each faction.

As Bretonnia I'm able to see them and build them no problem

I am running a LOT of mods; Radious, Tier 4 Minor Settlements, Higher Tier Starting Settlements, Cataph's TEB, among others; I think I'm able to get the Archecclestiamtium

Hahahahaha ok that's why, you're bound to run into some trouble running those with this mod man, but interesting to know that it hasn't crashed playing those Mods together

Yeah, it seems to be a bit of a crapshoot as to which Landmarks I get, but I can get most of them

Some suggestion: (sorry for gramatic errors.) and probably more when i get some ideas

Norsca:
-Darkshard tradenode
A building close to the chaos waste and what will soon be the gate into Uzkulak. Have a building or some tradehub were you only can recruit Hellcannons. As it is from Chaos Dwarf traders come and have sold them to you at this trade post. It can only be recruited there by Norsca. Maybe even some goblin slaves or something like that.

-Coffee plant farms. Skeggi.
A farm building which would make armies have more movements in the region and regions close to it. And it would give public order.

Dwarfs:
-Grand Harbor of Barak-Varr
A dwarven version of either the marienburg harbor. Gives you alot of gold and trade. Gives increase in output of tradegods.

-Dragonthrone of Karak-Azul.
A building which would give bonuses for armies in the region and border regions when attacking greenskins and monsters. As the dwarfs of Karak-Azul have been cut off from the other dwarfs and is fighting them often.

-Temple to the Ansestor gods. Karak-Zorn.
As Karak Zorn was lost long ago and cut off. It would have alot of ancient buildings and traditions left from the old days. As it is said it was lost before the colapse of the Karaz Ankor. It would give the bonuses of Monmument of Grimnir and a Rune forge.

-Mines of Zorn
Expensive building. As it is said in the lore Karak-Zorn was wealthy in gold, jewels and other treasures. It had so much of it. It is said they used gold coins and diamonds as normal copper coins. So this mine would give both Gold and Jewels. But cost alot of money to build. But also give alot. A win win. But it would cost to much to get early. So it would be a late gate investment. Maybe even Oathgold

Empire:
-Halfling farms. The Moot.
The farms of the moot should give higher growth than normal farms. And happiness to the settlement of moot. A combination of both a farm and a tavern. Public order and growth.

-All northern Empire settlements. Temple of Ulrik.
Gives higher anti corruption bonuses and a buff to all forces in the province when fighting chaos.

-Katarinas Icetower. Kislev.
The tower of the icequeen would make enemy armies suffer either attrition or get a large penalty to move in the provice as she sends ice blizzards at you. Slowing the armies down.

-Giant Cannon of Middenheim. Middenheim.
It would give large bonuses for Gunpowder units recruited there and gain attack and reload buffs when defending Middenheim. Towers on walls would do more damage aswell.

-Sewer system locks. Border princes, Estallia and Tilea.
Gives protection against Skaven corruption, Skaven cannot ambush attack (they can go into ambush stance, but their ambush attack passive is removed)

-Cursed walls of Praag.
Enemy and friendly units suffer moral damage from the walls. As the tortured souls scream at both friends and foe. Towers have higher damage and walls do moral damage.

Undead:
-Undead Throne of Reirkland. Vlad and Vampire counts
Need to have a captured Altdorf. It gives massive public order bonus. It would be the Clan angrund bonus when you retake Karak Eight peaks, but to the vampire counts. But the bonus would work on all units. Minus the dead units, such as skeletons, zombies etc.

-Library of Necronomicon. Undead.
Black pyramid. If captured you can build it there. It would generate undead corruption and give +10 in winds of magic, aswell as regneration for undead armies in battle as the area around the pyramid would resurect them if they fall in battle.

Elves:
-Open Vaults of Karak-A-Karak. High elves/dark elves
Need to be captured by any of the two factions. It would give extra ranks on new recruits as they are armed with ancient stolen weapons from the elves during the war of the beards. It would also give -100 relationship with all dwarven factions and it would give bonus damage against dwarves in the province.

Greenskins:
-Throne of GorkaMorka!! Greenskins.
A captured Karaz-A-Karak. it needs a teir V settlement and it would give public order, corruption defence and bonus XP for all recruits. This would also give -100 relationship with all dwarf factions.

I think Massif Orcal should have a landmark to rebuild the old watchtowers and strongholds which give the following effects: +10 public order and higher recruit level. Level 1 or 2 main building to build this landmark. for all factions except greenskins. I feel like there needs to be something to build at Massif Orcal, some benefits for conquering it
And
Albion should have the Ogham Stones(Waystones) giving the same buffs as the Athel Loren Waystones.
Keep up the great work and looking forward to the next update.

Skeggi - Norsca
Beast Pits (or some other name)- Gives small Gold Idols and Exotic Animal Cages trade goods.
Ability to train Feral Cold Ones and Feral Bastiladons.

A nice addition would be to make the landmarks, currently unique to a few factions available to all factions of the relevant group. An example would be the Clan Angrund building chain in Karak Eight Peaks, which is not available to other dwarf factions.

Here's a list of all the landmarks that (in my opinion) should be available to the rest of their respective races. There might be more, but these are all I can remember.

Dwarfs:
Clan Angrund building chain (Reinforced Citadel, Recovered Underhalls, Ancestor Tombs), Karak Eight Peaks

Norsca:
Cave of the Rocky Throne, Erengrad

Vampire Counts:
Mausoleum of the Mad Count, Castle Drakenhof

Greenskins:
Crooked Moon building chain (Deep Passageways, Looted Treasure Halls, Defiled Ancestor Tombs), Karak Eight Peaks

Skaven:
Clan Mors Headquarters, Karag Orrud
Clan Skryre building chain (Warpstone Telescope, Warpstone Tractor Beam), Skavenblight

Lizardmen:
Sacrificial Snake Pit of Sotek

Lorewise, I can't see a reason for the landmarks not being available to all members of the respective factions.

Corrupted version of the Grand temple of Ulric for vampires with buffs to Direwolves.