diff --git a/android/assets/jsons/Buildings.json b/android/assets/jsons/Buildings.json
index cabb1b00b0..e73d883e3f 100644
--- a/android/assets/jsons/Buildings.json
+++ b/android/assets/jsons/Buildings.json
@@ -61,6 +61,15 @@
 		unique:"+1 Science Per 2 Population",
 		requiredTech:"Writing"
 	},
+	{
+		name:"Paper Maker",
+		replaces:"Library",
+		uniqueTo:"China",
+		hurryCostModifier:25,
+		gold:2,
+		unique:"+1 Science Per 2 Population",
+		requiredTech:"Writing"
+	},
 	{
 		name:"Circus", 
 		requiredNearbyImprovedResources:["Ivory","Horses"]
diff --git a/core/src/com/unciv/models/gamebasics/Building.kt b/core/src/com/unciv/models/gamebasics/Building.kt
index 0547dfc6ad..3d01ea6623 100644
--- a/core/src/com/unciv/models/gamebasics/Building.kt
+++ b/core/src/com/unciv/models/gamebasics/Building.kt
@@ -32,6 +32,8 @@ class Building : NamedStats(), IConstruction{
     var cityStrength=0
     var cityHealth=0
     var xpForNewUnits=0
+    var replaces:String?=null
+    var uniqueTo:String?=null
 
     // Uniques
     var providesFreeBuilding: String? = null
@@ -99,6 +101,7 @@ class Building : NamedStats(), IConstruction{
     fun getDescription(forBuildingPickerScreen: Boolean, adoptedPolicies: HashSet<String>): String {
         val stats = getStats(adoptedPolicies)
         val stringBuilder = StringBuilder()
+        if(uniqueTo!=null) stringBuilder.appendln("Unique to $uniqueTo, replaces $replaces")
         if (!forBuildingPickerScreen) stringBuilder.appendln("{Cost}: $cost".tr())
         if (isWonder) stringBuilder.appendln("Wonder".tr())
         if (!forBuildingPickerScreen && requiredTech != null)
@@ -159,7 +162,10 @@ class Building : NamedStats(), IConstruction{
                             it.cityConstructions.isBuilding(name) || it.cityConstructions.isBuilt(name)
                         })
             return false
-        if (requiredBuilding != null && !construction.isBuilt(requiredBuilding!!)) return false
+        if (uniqueTo!=null && uniqueTo!=civInfo.civName) return false
+        if (GameBasics.Buildings.values.any { it.uniqueTo==civInfo.civName && it.replaces==name }) return false
+        if (requiredBuilding != null && !construction.isBuilt(requiredBuilding!!)
+                && construction.getBuiltBuildings().none{it.replaces==requiredBuilding}) return false
         if (requiredBuildingInAllCities != null && civInfo.cities.any { !it.cityConstructions.isBuilt(requiredBuildingInAllCities!!) })
             return false
         if(requiredBuildingInAllCities!=null && civInfo.cities.any {
diff --git a/core/src/com/unciv/models/gamebasics/tech/Technology.kt b/core/src/com/unciv/models/gamebasics/tech/Technology.kt
index e000a6f1b0..65f84de1bf 100644
--- a/core/src/com/unciv/models/gamebasics/tech/Technology.kt
+++ b/core/src/com/unciv/models/gamebasics/tech/Technology.kt
@@ -24,7 +24,9 @@ class Technology : ICivilopedia {
             enabledUnits = enabledUnits.filter { it.name !in replacedUnits}
             if(enabledUnits.isNotEmpty()) SB.appendln("{Units enabled}: "+enabledUnits.map { it.name.tr() + " ("+it.getShortDescription()+")" }.joinToString())
 
-            val enabledBuildings = GameBasics.Buildings.values.filter { it.requiredTech==name }
+            var enabledBuildings = GameBasics.Buildings.values.filter { it.requiredTech==name && (it.uniqueTo==null || it.uniqueTo==UnCivGame.Current.gameInfo.getPlayerCivilization().civName) }
+            val replacedBuildings = enabledBuildings.map { it.replaces }.filterNotNull()
+            enabledBuildings = enabledBuildings.filter { it.name !in replacedBuildings }
             val regularBuildings = enabledBuildings.filter { !it.isWonder }
             if(regularBuildings.isNotEmpty())
                 SB.appendln("{Buildings enabled}: "+regularBuildings.map { "\n * "+it.name.tr() + " ("+it.getShortDescription()+")" }.joinToString())