The Imperial State Building is located at the coordinates 375/450. You can attack the tower once every 24 hours for free. Subsequent attacks cost diamonds. 5 diamonds for the 2nd attack, 10 for the third, 15 for the forth and so on.

When you first attack the tower, only level 1 is available. New levels open up as you defeat each level. Troop types, amounts and their combat bonuses increase as you progress up the tower. Upon defeating a level there is a chance of winning an item, the same as if you were attacking a gang or murder inc tile.

Prizes include 3000 favors, 1000 kickbacks, Don's Sanction, Don's Blessing, level 11 armory items, level 11X armory items, 24 hour combat % bonuses, and 24 hour respect % bonuses. Levels 5, 8, and 10 also have a 'boss' that attacks with the troops. These levels have a small chance to award you with a new avatar.

The troop count changes each time you attack a given level. The difference is maybe around +/- 10% but there is no real data available at present.

Always use the Battle Calculator to estimate losses and use the bailout system so you never loose your best troops.