The sun wasn't shining, so it was easier to work - no walk this day as it started to rain! - but it got darker ;) I finally decided to use round shaped bricks for the wall above the fireplace and I did. With these bricks the fireplace looks more like the castle's one. This way the costruction of the walls was over. As I am unpatient person (this is no good when you work with miniatures - I know, no good at all, but what can I do about it?;)) and there was nothing more to build, I put the first layer of acrylic paint on the walls. The walls inside were painted dark grey, the outside ones - light grey and the fireplace - black.
The office is 52cm long, 32cm wide and 22cm high. I used 3 boxes of Teifoc bricks, that is around 780 bricks overall:)