Im not sure if ZOS recently updated this page, but the map that appeared on it gave us a strategic view of the PvP zone

http://static.elderscrollsonline.com/assets/img/game-guide/ava-epicbattles.jpg

http://www.elderscrollsonline.com/en/game-guide/the-alliance-war

The updated page also goes a bit more in-depth on PvP

The page itself also has new information about what events we will see in PvP.

The three alliances do battle in the region of Cyrodiil, seeking to control the Imperial City and with it, the Ruby Throne of Tamriel. Each alliance must wrest control of strategic territories from the others, including massive fortresses, each with supporting farms, lumber mills, and other valuable resources.

Battles are concentrated around these resources and strongholds. Control of certain resources will extend the alliance’s influence in the region and help them take control of the Imperial City, and ultimately, control of the Ruby Throne itself.

Can you seize enough territory to control the Ruby Throne?

Elder Scrolls are artifacts of immense power that aid an alliance in the ongoing battle to control Tamriel by conferring bonuses to every member of that alliance. Each alliance has a special stronghold in Cyrodiil where their Elder Scrolls are kept and protected – but enemy alliances can break in and take them if they are not guarded properly. Once access is gained and a Scroll taken, it must be taken back across Cyrodiil and placed in the alliance’s stronghold. Only then are the bonuses of the Scroll bestowed upon all the members of that alliance.

Capture an Elder Scroll, protect it, and return it to your alliance’s stronghold to wield its power and gain bonuses.

The battles for keeps and resources require more than the clash of steel. Alliances must use massive siege weapons to break down walls, smash open doors, and obliterate the armies of their opponents.

Everything from trebuchets and catapults to ballistae and battering rams are available for players to capture and use, allowing them to demolish the stone walls of keeps and collapse massive gates to gain entrance to heavily defended strongholds.