Today, the increasingly expanded or augmented reality gives us the opportunity to see the world differently. The insertion of the computer projection into the physical world is becoming increasingly popular virtual object imaging technology. The system operates with the help of Android OS by performing real-time mathematical calculations. It merges the image of the phone camera and the generated 3D model, overlaps the real images and sounds in a natural human environment. While moving along with the phone, the position is followed, so the overlaid generated computer image remains connected to the physical world. It allows you to move freely in an environment of augmented reality – zoom in / out of a 3D object. This project is dedicated to the restoration of Kaunas Castle. The generated 3D model is to be located on the existing castle structure, in this way giving the user an opportunity to see the previous structure. The system of an augmented reality for rendering, checking, or refurbishing architectural constructions, provides completely new possibilities for restoring or creating a new structure or other selected object.