Bulgaria is a wonderful destination with many sights that you can visit with a rental car. Here are some of them:
1. Sofia: Saint Alexander Nevsky Cathedral, the National Palace of Culture, Boyan Church and many museums.
2. Rila Monastery: It is located in the Rila mountain and is part of the UNESCO world cultural heritage.
3. Plovdiv: An ancient city with many Roman and Thracian archaeological sites, as well as beautiful Old Plovdiv with narrow streets and renovated houses.
4. Veliko Tarnovo: The city of the kings and capital of Medieval Bulgaria, with the Tsarevets fortress and the Arbanasi architectural reserve.
5. Pirin Mountains: For nature lovers, this national park offers incredible opportunities for hiking and exploring the high peaks and lakes.
6. Black Sea coast: Visit the resorts such as Golden Sands, Nessebar, Sunny Beach and others where you can enjoy the sea and the beach.
7. Rose Valley: Famous for its rose fields and rose oil production.
8. Melnik: The smallest town in Bulgaria, famous for its wines and sand pyramids.
9. Bachkovo Monastery: Another monastery included in the UNESCO World Heritage List, located near the city of Plovdiv.
10. The Seven Rila Lakes: A beautiful complex of seven lakes in the Rila Mountains.
11. Vratsa: The "Ledenika" cave and the nearby "Magurata" with their impressive cave formations.
12. Rhodopes: A mountainous region with many panoramic landscapes and traditional villages.
These are just some of the many interesting places that you can visit in Bulgaria with a rental car. However, before you leave, make sure you meet all the necessary documents and travel requirements.