From Civ World

The Build Menu shows the player what Buildings they can build in their City, as well as what military units they can build for their army. The menu is accessed via the Build button, which replaces the City button on the main taskbar when the player is viewing their city.

The Build Menu shows the basic House and food resources at the top, then all the buildings the player can build, and finally all the military units they can build.

Clicking on a building item will return the player to their City and give them a cursor they can use to place the new building in the city.

Clicking on a military unit will add it to the player's army. Newly built units are visible on the Armies screen and usable in battles right away.

Do note that many of the common buildings (and also the Move/Recycle functionality) can be accessed while viewing your city by using Keyboard Shortcuts.

Move/Recycle

A special item on the Build Menu, the Move/Recycle item allows the player to move buildings around in their city or recycle them to regain a portion of the production used to build them.

When Move/Recycle is clicked, the player will be returned to their city and can choose which building they wish to move or recycle. The amount of production you will get back will be shown as you hover over the structure. Example: Small Benefit Buildings and Houses will return all Production resources back to your City, but an upgraded building, Village Green, or a Guard Tower will only give you back a portion of those resources.

The percentage of the total cost of the building recovered when recycled is as follows:

Houses	Total value
Small Benefit Building	Total value		Small Guard Tower	1/2 of total value
Modest Benefit Building	3/4 of total value		Modest Guard Tower	3/8 of total value
Large Benefit Building	2/3 of total value		Large Guard Tower	1/3 of total value
Ginormous Benefit Building	5/8 of total value		Ginormous Guard Tower	5/16 of total value

Clicking on a building will remove it from the map and give the player a cursor to place it somewhere else. If they click on a different tile, the building will be moved there. If they reopen the Build Menu, the building will be recycled.

Important to take note that you cannot move upgraded buildings. They will be converted back to small buildings when moved.