Your Senate is the backbone of your city.  It controls your maximum building levels, your hero's maximum levels.  Here you will be able to see most everything about your city.  When you enter your Senate, you will see your Bureau, Castellan, Rename your City, All your Cities, Any Goblins, your Annexed Lands, and Any cities that you have seized.

Bureau - This is where you will see your gold and resource production, as well as any bonuses.  You can change your taxes here, and see how much food your troops are consuming.

Castellan - You can choose any of your hero's to be the Castellan of your city.  The Castellan, when appointed, will help you to decrease your building construction, as well as increase your resource production.  The amount of time decreased on building production and increased on resource production will be based on your chosen hero's intellect.

Rename - You can rename your city once a day here.

All Cities - You can view your city and sub cities here.  You may also abandon your cities in this tab.

Goblins - Here you can see where and if you have placed any goblins, and will also see how much resource they have stolen from the cities you have placed them on.

Annexed Land - Here you can see if any goblins have been placed on your city or any of your sub cities.  You will also be able to see how much resource the goblins have stolen from you.

Seized Cities - Here you can see all of the cities that you have seized.  You will be able to view what troops you have there, levy resources for troops, and recall your levied troops back to your city.  You will also be able to guard the city with your own troops, or abandon the city from here.