Historical Sites and Monuments:
1. Brandenburg Gate: Iconic gateway in Berlin, symbol of German reunification.
2. Berlin Wall Memorial: Remnants of the Berlin Wall, a poignant reminder of division and freedom.
3. Neuschwanstein Castle: Romantic fairytale castle, inspired by Wagner's operas.
4. Cologne Cathedral: Imposing gothic cathedral, one of the largest in Europe.
5. Reichstag Building: Historic parliament building, now home to the German Bundestag.
6. Charlottenburg Palace: Royal residence in Berlin, showcasing Prussian history.
7. Dresden Frauenkirche: Rebuilt church, symbol of Dresden's resilience.
8. Hohenschwangau Castle: Picturesque castle, near Neuschwanstein, home to King Ludwig II.
9. The Residenz, Munich: Former palace of Bavarian rulers, now a museum.
10. Heidelberg Castle: Romantic castle ruins, overlooking the city of Heidelberg.
Cultural and Artistic Landmarks:
11. The Deutsches Museum, Munich: World-renowned science and technology museum.
12. The Pergamon Museum, Berlin: Home to ancient world artifacts, including the Pergamon Altar.
13. The Alte Pinakothek, Munich: Housing a collection of European paintings from the Middle Ages to the 18th century.
14. The Bauhaus Dessau: Famous design school, a UNESCO World Heritage Site.
15. The Bayreuth Festspielhaus: Dedicated to Wagnerian opera, a unique architectural masterpiece.
Natural Wonders and Landscapes:
16. Black Forest: Mountainous region with lush forests and charming villages.
17. The Bavarian Alps: Home to Germany's highest peak, the Zugspitze, and stunning mountain scenery.
18. The Rhine Valley: Picturesque river valley, dotted with vineyards and castles.
19. The Baltic Sea Coast: Sandy beaches, coastal towns, and historical lighthouses.
20. The Wadden Sea: Unique natural habitat, a UNESCO World Heritage Site.
This list is just a starting point, and there are many other fascinating landmarks and attractions to discover in Germany. Your personal interests and preferences will ultimately determine what constitutes your "top twenty" landmarks.