Only certain items can be sold. Ruins, which are discovered when clearing Forests, can be sold after they have been explored. To do this, you will need to tap the explored ruin and click “Sell”. Buildings cannot be sold, though some, such as wonders, can be replaced with Crowns. 

On rare occasions, players may experience a loss of progress when constructing or upgrading a building, particularly on slow Internet connections. If you are experiencing this issue on a regular basis, please make sure you are have a stable WI-FI connection. 

If you do lose progress to your upgrade or building you won’t also lose the money/food/crowns spent on it. 

Changing your Wonder is simple -- tap the Wonder you'd like to change > Replace. By tapping ' Replace' you will have access to switch the Wonder for that particular Age. 

In order to change your Wonder, you must have 600 available Crowns and all of your Citizens must be available. Note that performing this change will instantly change your Wonder, meaning that you will not have to spend any additional resources.

This serves as a penalty for canceling an upgrade. However, if you cancel the upgrade within the first minute, you will be awarded 100% resource return.

Players who purchase the Starter Pack are unlocking the Industrial Age house earlier to give their budding civilization a few helping hands. 

Players who haven’t purchased the Starter Pack will gain access to a new house at the Store in Industrial Age. 

Every area of the game is accessible to players as they advance in age, regardless of whether they invest real money into it or not.