1. What material is the Eiffel Tower primarily constructed from?

2. What unique masonry technique was used by the Incas to build Machu Picchu without mortar?

3. What unusual food ingredient was used in the mortar to strengthen the Great Wall during the Ming Dynasty?

4. What distinguishes the Blue Mosque's exterior from most other Ottoman mosques built at the time?

5. Which desert flower served as the design inspiration for the Burj Khalifa's footprint?

6. What is the official name of the distinctive orange color used on the Golden Gate Bridge?

7. What was the meeting place of the Roman Senate located within the Forum?

8. Until 2018, which statue held the record for being the tallest in the world?

9. What type of movable bridge mechanism is used to raise the spans of Tower Bridge?

10. What material covers the exterior of the Guggenheim Museum Bilbao, giving it its shimmering, scaly appearance?

11. What did the Old Russian word for 'Red' (krasnaya) also mean when the square was named?

12. What is unique about Djemaa el-Fna's UNESCO recognition?

13. The Clementinum Library is a world-renowned example of which architectural and artistic style?

14. The shape of the modern Bibliotheca Alexandrina is intended to represent what celestial object?

15. Unlike the Panama Canal, why does the Suez Canal not require a system of locks?

16. What material were the chandeliers in the Chapel of St. Kinga carved from?

17. What technology is primarily used to propel the water in the Bellagio Fountains to such extreme heights?

18. What technology was used to ensure the precise palm-tree shape was maintained during construction?

19. Which Bangkok temple is famous for the Reclining Buddha statue?

20. Which area in Bangkok is famous for vibrant nightlife?