The buildings panel is the left one on the control panel. It has the symbol of a hut, so it's easy to know where to click to reach it. When selected, the color of the hut icon will turn different from the other two.

To select a plan from the building panel, you have to have that particular building plan unlocked. If you have, mouse left click on it, and then left click on the floor where you want it placed. If you want to deselect a plan after you clicked a building, before you place it, just mouse right click anywhere.

 

It is divided in 10 sections. One you start the single player, you only have 1 building avaliable - the hut. As your journey goes, you will unlock other buildings to be avaliable on the buildings panel. When a building square has a symbol, it means you have that particular building unlocked and can build it anytime you want. When there is no symbol on a square, it means that you have not yet discovered that building (except the bottom right square, which is always empty). When there is a questionmark symbol on a square, it means that building can be discovered on this world. 

In some cases, a stone head can give you one shot of a building, so before you worship it, there will be a question mark on that building's square. After worshipping, the square will be filled with that building's icon - but you can only build it once. After building it, that building's square will turn to a questionmark again.

 

From top to bottom and left to right, the buildings on the building panel are:

 

- hut

- tower

- warrior training hut

- temple

- Spy training hut

- firewarrior training hut

- boat hut

- balloon hut

- fireplace (always avaliable on every level)

- empty square (there is no building to fit on this square)