diff --git a/src/main/java/nl/andrewlalis/crystalkeep/CrystalKeep.java b/src/main/java/nl/andrewlalis/crystalkeep/CrystalKeep.java
index 8e63300..7431a08 100644
--- a/src/main/java/nl/andrewlalis/crystalkeep/CrystalKeep.java
+++ b/src/main/java/nl/andrewlalis/crystalkeep/CrystalKeep.java
@@ -4,8 +4,11 @@ import javafx.application.Application;
 import javafx.fxml.FXMLLoader;
 import javafx.scene.Scene;
 import javafx.stage.Stage;
+import nl.andrewlalis.crystalkeep.control.MainViewController;
 import nl.andrewlalis.crystalkeep.model.Cluster;
+import nl.andrewlalis.crystalkeep.model.Model;
 import nl.andrewlalis.crystalkeep.model.Shard;
+import nl.andrewlalis.crystalkeep.model.serialization.ClusterLoader;
 import nl.andrewlalis.crystalkeep.model.serialization.ClusterSerializer;
 import nl.andrewlalis.crystalkeep.model.shards.LoginCredentialsShard;
 import nl.andrewlalis.crystalkeep.model.shards.TextShard;
@@ -17,7 +20,7 @@ import java.time.LocalDateTime;
 import java.util.Arrays;
 
 public class CrystalKeep extends Application {
-	public static void main(String[] args) throws IOException {
+	public static void main(String[] args) {
 		launch(args);
 	}
 
@@ -25,10 +28,28 @@ public class CrystalKeep extends Application {
 	public void start(Stage stage) throws Exception {
 		URL url = CrystalKeep.class.getClassLoader().getResource("ui/crystalkeep.fxml");
 		FXMLLoader loader = new FXMLLoader(url);
+		Model model = new Model();
+		loader.setController(new MainViewController(model));
 		var scene = new Scene(loader.load());
 		stage.setScene(scene);
 		stage.setTitle("CrystalKeep");
 		stage.sizeToScene();
+
+		ClusterLoader clusterLoader = new ClusterLoader();
+		Cluster rootCluster;
+		try {
+			rootCluster = clusterLoader.loadDefault();
+			System.out.println("Loaded existing root cluster.");
+		} catch (IOException e) {
+			rootCluster = new Cluster("Root");
+			rootCluster.addShard(new TextShard(rootCluster, "Example Shard", LocalDateTime.now(), "Hello world!"));
+			clusterLoader.saveDefault(rootCluster);
+			System.out.println("Saved root cluster on first load.");
+		}
+
+		model.setActiveCluster(rootCluster);
+		System.out.println(rootCluster);
+
 		stage.show();
 	}
 
diff --git a/src/main/java/nl/andrewlalis/crystalkeep/control/ClusterTreeViewController.java b/src/main/java/nl/andrewlalis/crystalkeep/control/ClusterTreeViewController.java
new file mode 100644
index 0000000..0b53e57
--- /dev/null
+++ b/src/main/java/nl/andrewlalis/crystalkeep/control/ClusterTreeViewController.java
@@ -0,0 +1,9 @@
+package nl.andrewlalis.crystalkeep.control;
+
+import javafx.fxml.FXML;
+import javafx.scene.control.TreeView;
+
+public class ClusterTreeViewController {
+	@FXML
+	TreeView<String> clusterTreeView;
+}
diff --git a/src/main/java/nl/andrewlalis/crystalkeep/control/MainViewController.java b/src/main/java/nl/andrewlalis/crystalkeep/control/MainViewController.java
new file mode 100644
index 0000000..75de4d2
--- /dev/null
+++ b/src/main/java/nl/andrewlalis/crystalkeep/control/MainViewController.java
@@ -0,0 +1,26 @@
+package nl.andrewlalis.crystalkeep.control;
+
+import javafx.event.ActionEvent;
+import javafx.fxml.FXML;
+import nl.andrewlalis.crystalkeep.model.Model;
+import nl.andrewlalis.crystalkeep.model.serialization.ClusterLoader;
+
+import java.io.IOException;
+
+public class MainViewController {
+	private final Model model;
+
+	public MainViewController(Model model) {
+		this.model = model;
+	}
+
+	@FXML
+	public void exit(ActionEvent event) {
+		System.out.println("Exiting...");
+		try {
+			new ClusterLoader().saveDefault(model.getActiveCluster());
+		} catch (IOException e) {
+			e.printStackTrace();
+		}
+	}
+}
diff --git a/src/main/java/nl/andrewlalis/crystalkeep/control/ShardDetailController.java b/src/main/java/nl/andrewlalis/crystalkeep/control/ShardDetailController.java
new file mode 100644
index 0000000..06f9cab
--- /dev/null
+++ b/src/main/java/nl/andrewlalis/crystalkeep/control/ShardDetailController.java
@@ -0,0 +1,4 @@
+package nl.andrewlalis.crystalkeep.control;
+
+public class ShardDetailController {
+}
diff --git a/src/main/java/nl/andrewlalis/crystalkeep/model/Model.java b/src/main/java/nl/andrewlalis/crystalkeep/model/Model.java
new file mode 100644
index 0000000..29a009a
--- /dev/null
+++ b/src/main/java/nl/andrewlalis/crystalkeep/model/Model.java
@@ -0,0 +1,12 @@
+package nl.andrewlalis.crystalkeep.model;
+
+import lombok.Getter;
+
+@Getter
+public class Model {
+	private Cluster activeCluster;
+
+	public void setActiveCluster(Cluster activeCluster) {
+		this.activeCluster = activeCluster;
+	}
+}
diff --git a/src/main/java/nl/andrewlalis/crystalkeep/model/serialization/ClusterLoader.java b/src/main/java/nl/andrewlalis/crystalkeep/model/serialization/ClusterLoader.java
new file mode 100644
index 0000000..4f5e55f
--- /dev/null
+++ b/src/main/java/nl/andrewlalis/crystalkeep/model/serialization/ClusterLoader.java
@@ -0,0 +1,25 @@
+package nl.andrewlalis.crystalkeep.model.serialization;
+
+import nl.andrewlalis.crystalkeep.model.Cluster;
+
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.file.Files;
+import java.nio.file.Path;
+
+public class ClusterLoader {
+	private static final Path CLUSTER_PATH = Path.of("clusters");
+	private static final Path DEFAULT_CLUSTER = CLUSTER_PATH.resolve("default.cts");
+
+	public Cluster loadDefault() throws IOException {
+		InputStream is = new FileInputStream(DEFAULT_CLUSTER.toFile());
+		return ClusterSerializer.clusterFromBytes(is, null);
+	}
+
+	public void saveDefault(Cluster cluster) throws IOException {
+		Files.createDirectories(CLUSTER_PATH);
+		byte[] bytes = ClusterSerializer.toBytes(cluster);
+		Files.write(DEFAULT_CLUSTER, bytes);
+	}
+}
diff --git a/src/main/java/nl/andrewlalis/crystalkeep/model/serialization/ClusterSerializer.java b/src/main/java/nl/andrewlalis/crystalkeep/model/serialization/ClusterSerializer.java
index 3c53750..fc89090 100644
--- a/src/main/java/nl/andrewlalis/crystalkeep/model/serialization/ClusterSerializer.java
+++ b/src/main/java/nl/andrewlalis/crystalkeep/model/serialization/ClusterSerializer.java
@@ -19,6 +19,10 @@ import java.util.Map;
 
 import static nl.andrewlalis.crystalkeep.model.serialization.ByteUtils.toInt;
 
+/**
+ * This serializer class offers some methods for reading and writing clusters
+ * from and to byte arrays.
+ */
 public class ClusterSerializer {
 	private static final Map<ShardType, ShardSerializer<?>> serializers = new HashMap<>();
 	static {
@@ -29,6 +33,7 @@ public class ClusterSerializer {
 	/**
 	 * Serializes a cluster to a byte array, including all shards and nested
 	 * clusters.
+	 * TODO: Use output stream instead of byte array.
 	 * @param cluster The cluster to serialize.
 	 * @return The byte array representing the cluster.
 	 * @throws IOException If an error occurs while writing the cluster.
diff --git a/src/main/resources/ui/clusters_view.fxml b/src/main/resources/ui/clusters_view.fxml
new file mode 100644
index 0000000..93bb4c6
--- /dev/null
+++ b/src/main/resources/ui/clusters_view.fxml
@@ -0,0 +1,18 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+<?import javafx.scene.control.Label?>
+<?import javafx.scene.control.TreeView?>
+<?import javafx.scene.layout.BorderPane?>
+
+<BorderPane xmlns="http://javafx.com/javafx"
+			xmlns:fx="http://javafx.com/fxml"
+			fx:controller="nl.andrewlalis.crystalkeep.control.ClusterTreeViewController"
+			prefWidth="200.0"
+>
+	<top>
+		<Label text="Clusters" BorderPane.alignment="TOP_CENTER"/>
+	</top>
+	<center>
+		<TreeView fx:id="clusterTreeView" prefWidth="200.0"/>
+	</center>
+</BorderPane>
diff --git a/src/main/resources/ui/crystalkeep.fxml b/src/main/resources/ui/crystalkeep.fxml
index 39352a8..8cdbdea 100644
--- a/src/main/resources/ui/crystalkeep.fxml
+++ b/src/main/resources/ui/crystalkeep.fxml
@@ -1,10 +1,25 @@
 <?xml version="1.0" encoding="UTF-8"?>
 
-<?import javafx.scene.control.*?>
-<?import javafx.scene.layout.*?>
+<?import javafx.scene.layout.BorderPane?>
+
+<?import javafx.scene.control.MenuBar?>
+<?import javafx.scene.control.Menu?>
+<?import javafx.scene.control.MenuItem?>
+
+<?import javafx.scene.layout.VBox?>
+<VBox xmlns:fx="http://javafx.com/fxml/1" fx:controller="nl.andrewlalis.crystalkeep.control.MainViewController">
+   <MenuBar>
+      <Menu text="File">
+         <MenuItem text="Exit" onAction="#exit" />
+      </Menu>
+   </MenuBar>
+   <BorderPane>
+      <left>
+         <fx:include source="clusters_view.fxml" />
+      </left>
+      <center>
+         <fx:include source="shard_detail.fxml" />
+      </center>
+   </BorderPane>
+</VBox>
 
-<BorderPane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="400.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/11.0.1" xmlns:fx="http://javafx.com/fxml/1">
-   <left>
-      <TreeView prefHeight="200.0" prefWidth="200.0" BorderPane.alignment="CENTER" />
-   </left>
-</BorderPane>
diff --git a/src/main/resources/ui/shard_detail.fxml b/src/main/resources/ui/shard_detail.fxml
new file mode 100644
index 0000000..787ff62
--- /dev/null
+++ b/src/main/resources/ui/shard_detail.fxml
@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+<?import javafx.scene.layout.AnchorPane?>
+<AnchorPane xmlns="http://javafx.com/javafx"
+			xmlns:fx="http://javafx.com/fxml"
+			fx:controller="nl.andrewlalis.crystalkeep.control.ShardDetailController"
+			prefHeight="400.0" prefWidth="600.0">
+
+</AnchorPane>