6. Indicate the objects of World Cultural and Natural Heritage.

Analysis of the map:

The map displays geographical features and a legend for 'Conventional Symbols'. However, none of the symbols or markings on the map correspond to or indicate sites of World Cultural or Natural Heritage recognized by UNESCO.

Task 6: Indicate the objects of World Cultural and Natural Heritage.

To perform this task, the map would need to feature specific markers, icons, or labels that denote UNESCO World Heritage sites located within the Volga region. This information is not present in the current visualization.

Conclusion: I am unable to complete task 6 based solely on the visual information present in the image.