diff --git a/core/src/com/unciv/models/ruleset/Building.kt b/core/src/com/unciv/models/ruleset/Building.kt
index e71302915f..61ec84f3ca 100644
--- a/core/src/com/unciv/models/ruleset/Building.kt
+++ b/core/src/com/unciv/models/ruleset/Building.kt
@@ -37,6 +37,7 @@ class Building : RulesetStatsObject(), INonPerpetualConstruction {
     var isNationalWonder = false
     fun isAnyWonder() = isWonder || isNationalWonder
     var requiredBuilding: String? = null
+    @Deprecated("As of 3.18.15 - replace with RequiresBuildingInAllCities unique")
     var requiredBuildingInAllCities: String? = null
 
     /** A strategic resource that will be consumed by this building */
@@ -237,17 +238,12 @@ class Building : RulesetStatsObject(), INonPerpetualConstruction {
             textList += FormattedLine(stats.joinToString(", ", "{Cost}: "))
         }
 
-        if (requiredTech != null || requiredBuilding != null || requiredBuildingInAllCities != null)
-            textList += FormattedLine()
         if (requiredTech != null)
             textList += FormattedLine("Required tech: [$requiredTech]",
                 link="Technology/$requiredTech")
         if (requiredBuilding != null)
             textList += FormattedLine("Requires [$requiredBuilding] to be built in the city",
                 link="Building/$requiredBuilding")
-        if (requiredBuildingInAllCities != null)
-            textList += FormattedLine("Requires [$requiredBuildingInAllCities] to be built in all cities",
-                link="Building/$requiredBuildingInAllCities")
 
         val resourceRequirements = getResourceRequirements()
         if (resourceRequirements.isNotEmpty()) {
@@ -596,25 +592,11 @@ class Building : RulesetStatsObject(), INonPerpetualConstruction {
             if (civInfo.cities.any { it.cityConstructions.isBuilt(name) })
                 rejectionReasons.add(RejectionReason.NationalWonderAlreadyBuilt)
 
-            if (requiredBuildingInAllCities != null && civInfo.gameInfo.ruleSet.buildings[requiredBuildingInAllCities!!] == null) {
-                rejectionReasons.add(RejectionReason.InvalidRequiredBuilding)
-            } else {
-                if (requiredBuildingInAllCities != null
-                    && civInfo.cities.any {
-                        !it.isPuppet && !it.cityConstructions
-                        .containsBuildingOrEquivalent(requiredBuildingInAllCities!!)
-                    }
-                ) {
-                    rejectionReasons.add(RejectionReason.RequiresBuildingInAllCities
-                        .apply { errorMessage = "Requires a [${civInfo.getEquivalentBuilding(requiredBuildingInAllCities!!)}] in all cities"})
-                }
+            if (civInfo.cities.any { it != cityConstructions.cityInfo && it.cityConstructions.isBeingConstructedOrEnqueued(name) })
+                rejectionReasons.add(RejectionReason.NationalWonderBeingBuiltElsewhere)
 
-                if (civInfo.cities.any { it != cityConstructions.cityInfo && it.cityConstructions.isBeingConstructedOrEnqueued(name) })
-                    rejectionReasons.add(RejectionReason.NationalWonderBeingBuiltElsewhere)
-
-                if (civInfo.isCityState())
-                    rejectionReasons.add(RejectionReason.CityStateNationalWonder)
-            }
+            if (civInfo.isCityState())
+                rejectionReasons.add(RejectionReason.CityStateNationalWonder)
         }
 
         if (hasUnique(UniqueType.SpaceshipPart)) {
diff --git a/core/src/com/unciv/models/ruleset/Ruleset.kt b/core/src/com/unciv/models/ruleset/Ruleset.kt
index 2881e2b272..9fc2307872 100644
--- a/core/src/com/unciv/models/ruleset/Ruleset.kt
+++ b/core/src/com/unciv/models/ruleset/Ruleset.kt
@@ -22,6 +22,7 @@ import com.unciv.models.stats.INamed
 import com.unciv.models.stats.NamedStats
 import com.unciv.models.stats.Stat
 import com.unciv.models.stats.Stats
+import com.unciv.models.translations.fillPlaceholders
 import com.unciv.models.translations.tr
 import com.unciv.ui.utils.colorFromRGB
 import kotlin.collections.set
@@ -179,6 +180,9 @@ class Ruleset {
 
         val buildingsFile = folderHandle.child("Buildings.json")
         if (buildingsFile.exists()) buildings += createHashmap(jsonParser.getFromJson(Array<Building>::class.java, buildingsFile))
+        for(building in buildings.values)
+            if(building.requiredBuildingInAllCities != null)
+                building.uniques.add(UniqueType.RequiresBuildingInAllCities.text.fillPlaceholders(building.requiredBuildingInAllCities!!))
 
         val terrainsFile = folderHandle.child("Terrains.json")
         if (terrainsFile.exists()) {
@@ -491,8 +495,9 @@ class Ruleset {
                 lines += "${building.name} replaces ${building.replaces} which does not exist!"
             if (building.requiredBuilding != null && !buildings.containsKey(building.requiredBuilding!!))
                 lines += "${building.name} requires ${building.requiredBuilding} which does not exist!"
-            if (building.requiredBuildingInAllCities != null && !buildings.containsKey(building.requiredBuildingInAllCities!!))
-                lines += "${building.name} requires ${building.requiredBuildingInAllCities} in all cities which does not exist!"
+            if (building.requiredBuildingInAllCities != null)
+                lines.add("${building.name} contains 'requiredBuildingInAllCities' - please convert to a \"" +
+                        UniqueType.RequiresBuildingInAllCities.text.fillPlaceholders(building.requiredBuildingInAllCities!!)+"\" unique", RulesetErrorSeverity.Warning)
             for (unique in building.uniqueObjects)
                 if (unique.placeholderText == "Creates a [] improvement on a specific tile" && !tileImprovements.containsKey(unique.params[0]))
                     lines += "${building.name} creates a ${unique.params[0]} improvement which does not exist!"