Every Town is made up of a collection of facilities that all serve different purposes. Some are spawn points, some are supply depots, but all of them can be captured. A capture building will be present for every facility showing the flag of the country that currently controls that facility.
A capture office.
The most common type of facility is found inside CP's, and is the depot, city, or factory facility. These will have a Capture Office (also known as a flag building or radio building) near them, where a radio table will exist and can be captured.
A forward base.
The other common type of facility is the FB or Forward Base. These cannot be captured, but rather can be destroyed (by using the satchel charges carried by sappers) to close one FB of the pair, and open the other, under new ownership.