Index: ps/trunk/binaries/data/mods/public/simulation/ai/petra/baseManager.js
===================================================================
--- ps/trunk/binaries/data/mods/public/simulation/ai/petra/baseManager.js
+++ ps/trunk/binaries/data/mods/public/simulation/ai/petra/baseManager.js
@@ -245,12 +245,37 @@
 };
 
 /**
- * Returns the position of the best place to build a new dropsite for the specified resource
+ * @return {Object} - The position of the best place to build a new dropsite for the specified resource,
+ *			its quality and its template name.
  */
-PETRA.BaseManager.prototype.findBestDropsiteLocation = function(gameState, resource)
+PETRA.BaseManager.prototype.findBestDropsiteAndLocation = function(gameState, resource)
 {
+	let bestResult = {
+		"quality": 0,
+		"pos": [0, 0]
+	};
+	for (const templateName of gameState.ai.HQ.buildManager.findStructuresByFilter(gameState, API3.Filters.isDropsite(resource)))
+	{
+		const dp = this.findBestDropsiteLocation(gameState, resource, templateName);
+		if (dp.quality < bestResult.quality)
+			continue;
+		bestResult = dp;
+		bestResult.templateName = templateName;
+	}
+	return bestResult;
+};
+
+/**
+ * Returns the position of the best place to build a new dropsite for the specified resource and dropsite template.
+ */
+PETRA.BaseManager.prototype.findBestDropsiteLocation = function(gameState, resource, templateName)
+{
+	const template = gameState.getTemplate(gameState.applyCiv(templateName));
+
+	// CCs and Docks are handled elsewhere.
+	if (template.hasClass("CivCentre") || template.hasClass("Dock"))
+		return { "quality": 0, "pos": [0, 0] };
 
-	let template = gameState.getTemplate(gameState.applyCiv("structures/{civ}/storehouse"));
 	let halfSize = 0;
 	if (template.get("Footprint/Square"))
 		halfSize = Math.max(+template.get("Footprint/Square/@depth"), +template.get("Footprint/Square/@width")) / 2;
@@ -430,17 +455,17 @@
 			let ratio = this.gatherers[type].lost / total;
 			if (ratio > 0.15)
 			{
-				let newDP = this.findBestDropsiteLocation(gameState, type);
-				if (newDP.quality > 50 && gameState.ai.HQ.canBuild(gameState, "structures/{civ}/storehouse"))
-					queues.dropsites.addPlan(new PETRA.ConstructionPlan(gameState, "structures/{civ}/storehouse", { "base": this.ID, "type": type }, newDP.pos));
+				const newDP = this.findBestDropsiteAndLocation(gameState, type);
+				if (newDP.quality > 50 && gameState.ai.HQ.canBuild(gameState, newDP.templateName))
+					queues.dropsites.addPlan(new PETRA.ConstructionPlan(gameState, newDP.templateName, { "base": this.ID, "type": type }, newDP.pos));
 				else if (!gameState.getOwnFoundations().filter(API3.Filters.byClass("CivCentre")).hasEntities() && !queues.civilCentre.hasQueuedUnits())
 				{
 					// No good dropsite, try to build a new base if no base already planned,
 					// and if not possible, be less strict on dropsite quality.
 					if ((!gameState.ai.HQ.canExpand || !gameState.ai.HQ.buildNewBase(gameState, queues, type)) &&
 					    newDP.quality > Math.min(25, 50*0.15/ratio) &&
-					    gameState.ai.HQ.canBuild(gameState, "structures/{civ}/storehouse"))
-						queues.dropsites.addPlan(new PETRA.ConstructionPlan(gameState, "structures/{civ}/storehouse", { "base": this.ID, "type": type }, newDP.pos));
+					    gameState.ai.HQ.canBuild(gameState, newDP.templateName))
+						queues.dropsites.addPlan(new PETRA.ConstructionPlan(gameState, newDP.templateName, { "base": this.ID, "type": type }, newDP.pos));
 				}
 			}
 			this.gatherers[type].nextCheck = gameState.ai.playedTurn + 20;
Index: ps/trunk/binaries/data/mods/public/simulation/ai/petra/buildManager.js
===================================================================
--- ps/trunk/binaries/data/mods/public/simulation/ai/petra/buildManager.js
+++ ps/trunk/binaries/data/mods/public/simulation/ai/petra/buildManager.js
@@ -98,22 +98,31 @@
 
 
 /**
- * Get the first buildable structure with a given class
- * TODO when several available, choose the best one
+ * Get the buildable structures passing a filter.
  */
-PETRA.BuildManager.prototype.findStructureWithClass = function(gameState, classes)
+PETRA.BuildManager.prototype.findStructuresByFilter = function(gameState, filter)
 {
+	const result = [];
 	for (let [templateName, count] of this.builderCounters)
 	{
-		if (count == 0 || gameState.isTemplateDisabled(templateName))
+		if (!count || gameState.isTemplateDisabled(templateName))
 			continue;
 		let template = gameState.getTemplate(templateName);
 		if (!template || !template.available(gameState))
 			continue;
-		if (MatchesClassList(template.classes(), classes))
-			return templateName;
+		if (filter.func(template))
+			result.push(templateName);
 	}
-	return undefined;
+	return result;
+};
+
+/**
+ * Get the first buildable structure with a given class
+ * TODO when several available, choose the best one
+ */
+PETRA.BuildManager.prototype.findStructureWithClass = function(gameState, classes)
+{
+	return this.findStructuresByFilter(gameState, API3.Filters.byClassesOr(classes))[0];
 };
 
 PETRA.BuildManager.prototype.hasBuilder = function(template)
Index: ps/trunk/binaries/data/mods/public/simulation/ai/petra/queueplanBuilding.js
===================================================================
--- ps/trunk/binaries/data/mods/public/simulation/ai/petra/queueplanBuilding.js
+++ ps/trunk/binaries/data/mods/public/simulation/ai/petra/queueplanBuilding.js
@@ -119,7 +119,7 @@
 		// recompute the best dropsite location in case some conditions have changed
 		let base = HQ.getBaseByID(this.metadata.base);
 		let type = this.metadata.type ? this.metadata.type : "wood";
-		let newpos = base.findBestDropsiteLocation(gameState, type);
+		const newpos = base.findBestDropsiteLocation(gameState, type, template._templateName);
 		if (newpos && newpos.quality > 0)
 		{
 			let pos = newpos.pos;
Index: ps/trunk/binaries/data/mods/public/simulation/ai/petra/startingStrategy.js
===================================================================
--- ps/trunk/binaries/data/mods/public/simulation/ai/petra/startingStrategy.js
+++ ps/trunk/binaries/data/mods/public/simulation/ai/petra/startingStrategy.js
@@ -545,11 +545,10 @@
 	}
 
 	// immediatly build a wood dropsite if possible.
-	let template = gameState.applyCiv("structures/{civ}/storehouse");
-	if (!gameState.getOwnEntitiesByClass("Storehouse", true).hasEntities() && this.canBuild(gameState, template))
+	if (!gameState.getOwnEntitiesByClass("DropsiteWood", true).hasEntities())
 	{
-		let newDP = this.baseManagers[1].findBestDropsiteLocation(gameState, "wood");
-		if (newDP.quality > 40)
+		const newDP = this.baseManagers[1].findBestDropsiteAndLocation(gameState, "wood");
+		if (newDP.quality > 40 && this.canBuild(gameState, newDP.templateName))
 		{
 			// if we start with enough workers, put our available resources in this first dropsite
 			// same thing if our pop exceed the allowed one, as we will need several houses
@@ -557,16 +556,16 @@
 			if (numWorkers > 12 && newDP.quality > 60 ||
 				gameState.getPopulation() > gameState.getPopulationLimit() + 20)
 			{
-				let cost = new API3.Resources(gameState.getTemplate(template).cost());
+				const cost = new API3.Resources(gameState.getTemplate(newDP.templateName).cost());
 				gameState.ai.queueManager.setAccounts(gameState, cost, "dropsites");
 			}
-			gameState.ai.queues.dropsites.addPlan(new PETRA.ConstructionPlan(gameState, template, { "base": this.baseManagers[1].ID }, newDP.pos));
+			gameState.ai.queues.dropsites.addPlan(new PETRA.ConstructionPlan(gameState, newDP.templateName, { "base": this.baseManagers[1].ID }, newDP.pos));
 		}
 	}
 	// and build immediately a corral if needed
 	if (this.needCorral)
 	{
-		template = gameState.applyCiv("structures/{civ}/corral");
+		const template = gameState.applyCiv("structures/{civ}/corral");
 		if (!gameState.getOwnEntitiesByClass("Corral", true).hasEntities() && this.canBuild(gameState, template))
 			gameState.ai.queues.corral.addPlan(new PETRA.ConstructionPlan(gameState, template, { "base": this.baseManagers[1].ID }));
 	}