Prerequisites: none

A village's builders live in the main building. The higher its level, the faster your builders will complete the construction of new buildings. 

When you have buildings queued for construction and your main building is destroyed or upgraded, the building times will not be recalculated. This is exactly the same as prerequisites for buildings being destroyed: statistics are calculated when you click the 'upgrade to level X' link and are not recalculated again. The only exception for this is the prerequisite that the village has to be the capital. 

Demolishing
If you do not need a building any more, you can order your builders to demolish it. This requires a main building at level 10 or above.
To remove a building you have three possibilites:

• Level by level with the respective destruction time
• Level by level by using the Gold instant completion feature to finish it without any destruction time
• The complete building at once by using the implemented Gold instant complete destruction feature

If you don’t have enough crop production, it may not be possible to upgrade the Main Building. See our article about Crop Production for more details..

The level dependent attributes (such as construction costs and generated culture points) can be found here.
For the full table of construction times click this link for server with 1x speed, this link for server with 2x speed and this link for server with 3x speed.