The Building Modes Menu allows to make changes to the city such as moving or selling buildings and reconstructing the whole city. Building modes menu is opened when the Build button is pressed.
On the desktop version the building modes menu contains 4 buttons. On the mobile version there are 3 buttons (no cancel button). Buttons from left to right are: Sell, Move, Close and Reconstruction Mode.
If no mode is selected players are still able to perform regular tasks such as collection of productions, aiding, solving quests etc. Even when the build menu is open.
The "Sell" mode allows to sell any building that is clicked upon.
To prevent selling buildings by mistake, a confirmation box will prompt up asking if the player really wants to sell the building. Additional check box is also present while selling special buildings or Great Buildings for additional confirmation whether the player actually wants to sell the building.
Roads and two-lane streets are sold without getting the prompt confirmation dialog box, to reduce clicking time. Hence, one has to be careful while using this mode.
The "Move" mode allows to select any building that is clicked upon for moving. The selected building can now be placed on any desirable location, provided the space is adequate.
A particular privilege available for desktop version users is that, if a building is placed on a location where there is only one object blocking the free space, then the shaded building turns blue. The selected building can then be placed, and the building formerly occupying the place becomes selected instead.
It is worth noting that the above privilege does not work if there are 2 or more buildings occupying the free space where the selected building is to be placed.
The "Close" button closes the selected building mode. On mobile version this button is absent. To close the building mode on mobile the button of the mode must be pressed again or the build menu itself must be closed.
For more information see the Reconstruction Mode.
The "reconstruction mode" helps players to rearrange the city by offering temporary storage for the buildings.