diff --git a/src/semeion/main.py b/src/semeion/main.py
index ad13fc2..775454d 100644
--- a/src/semeion/main.py
+++ b/src/semeion/main.py
@@ -1,8 +1,9 @@
-from .ui import GUI
-
+from .ui import MainWindow, SemeionInstance
 
 def main():
-    mainGui = GUI()
+    app = SemeionInstance()
+    window = MainWindow(app)
+    window.start()
     # TODO: Initialize logging here
     # TODO: Initialize llm client and qdrant client
     # TODO: start main window
diff --git a/src/semeion/ui/__init__.py b/src/semeion/ui/__init__.py
index 884d401..66faed6 100644
--- a/src/semeion/ui/__init__.py
+++ b/src/semeion/ui/__init__.py
@@ -1,3 +1,3 @@
-from .main_window import GUI
+from .main_window import MainWindow, SemeionInstance
 
-__all__ = ["GUI"]
\ No newline at end of file
+__all__ = ["MainWindow", "SemeionInstance"]
\ No newline at end of file
diff --git a/src/semeion/ui/main_window.py b/src/semeion/ui/main_window.py
index e641868..c64e52c 100644
--- a/src/semeion/ui/main_window.py
+++ b/src/semeion/ui/main_window.py
@@ -1,5 +1,94 @@
-from PySide6.QtWidgets import QMainWindow
+from PySide6.QtWidgets import QApplication, QWidget, QVBoxLayout, QLabel, QPushButton, QGridLayout, QLineEdit, QToolBar
+from PySide6.QtGui import QAction
+from PySide6.QtCore import Qt
 
-class GUI(QMainWindow):
+class SemeionInstance(QApplication):
     def __init__(self):
-        pass
\ No newline at end of file
+        super().__init__([])
+
+class MainWindow(QWidget):
+    def __init__(self, app: SemeionInstance):
+        super().__init__()
+        self.setWindowTitle("Semeion Interface")
+        self.setGeometry(100, 100, 800, 600)
+        self.app = app
+
+        self.main_layout = QVBoxLayout()
+        self.setLayout(self.main_layout)
+        
+        # Toolbar
+        self.toolbar = QToolBar()
+        self.main_layout.addWidget(self.toolbar)
+        action_CaseManager = QAction("Case", self)
+        action_IngestionManager = QAction("Ingest Artifacts", self)
+        action_ConnManager = QAction("Server Connections", self)
+        action_SettingsMenu = QAction("Settings", self)
+        action_AboutMenu = QAction("About", self)
+        self.toolbar.addAction(action_CaseManager)
+        self.toolbar.addAction(action_IngestionManager)
+        self.toolbar.addAction(action_ConnManager)
+        self.toolbar.addAction(action_SettingsMenu)
+        self.toolbar.addAction(action_AboutMenu)
+        
+        # spacing
+        self.main_layout.addStretch(1)
+        
+        # branding
+        self.brandingLabel = QLabel("S E M E I O N\n")
+        self.brandingLabel.setStyleSheet("font-size: 32px; font-weight: bold; font-family: Cantarell;")
+        self.main_layout.addWidget(self.brandingLabel, alignment=Qt.AlignmentFlag.AlignCenter)
+        
+        # search Input       
+        self.searchInput = QLineEdit()
+        self.searchInput.setPlaceholderText("Natural Language Search...")
+        self.searchInput.setFixedWidth(400)
+        self.searchInput.setMinimumHeight(30)
+        self.searchInput.setStyleSheet("""
+                                       QLineEdit {
+                                           border: 1px solid #ddd;
+                                           border-radius: 24px;
+                                           padding: 10px 20px;
+                                           font-size: 16px;
+                                       }
+                                       QLineEdit:focus {
+                                           border: 1px solid #aaa;
+                                           outline: none;
+                                       }""")
+        self.main_layout.addWidget(self.searchInput, alignment=Qt.AlignmentFlag.AlignCenter)
+        self.main_layout.addSpacing(10)
+        
+        self.executeButton = QPushButton("Execute")
+        self.executeButton.setAttribute(Qt.WidgetAttribute.WA_Hover)
+        self.executeButton.setStyleSheet("""
+            QPushButton {
+                padding: 8px 16px;
+                font-size: 16px;
+                border-radius: 12px;
+                background-color: #808080;
+                color: white;
+                border: 1px solid #6e6e6e;
+            }
+            QPushButton:hover {
+                background-color: #6e6e6e;
+            }
+            QPushButton:pressed {
+                background-color: #5e5e5e;
+            }
+        """)
+        self.main_layout.addWidget(self.executeButton, alignment=Qt.AlignmentFlag.AlignCenter)
+        self.executeButton.clicked.connect(self.execute_from_input)
+        
+        self.main_layout.addStretch(1)
+        
+
+    def start(self):
+        self.show()
+        self.app.exec()
+        
+    def execute_from_input(self):
+        query = self.searchInput.text().strip()
+        if not query:
+            return
+        # TODO: implement logic
+        print("Execute query:", query)
+        
\ No newline at end of file