The application is an addition to postcards with a picture of the Kaliningrad Royal Castle, which cannot be seen in the real world. By purchasing a postcard with an image of the Royal Castle (http://www.ekskursia39.ru/) and downloading the application, you will be able to see the castle in 3D in miniature and listen to a short historical background about the castle.
To use the application, follow the following instructions:
1. Install the application
2. Point to the Postcards image
3. On the right side, click on the speaker icon to turn on the audio guide