We need 6 small wonders that must be built before BT

[wieder]

BT here is Bismarck Tower.

The game can be ended when someone builds the Bismarck Tower. In this scenario it's not about killing everyone or reaching the stars. Sure, you can do both of those but the game will also end with this wonder.

Small Wonder 1 can be built once some tech of the late 19th centure is known. The tech will be decided later.
Small Wonder 2 can be built once the player has Small Wonder 1.
Small Wonder 3 can be built once the player has Small Wonder 2.
Small Wonder 4 can be built once the player has Small Wonder 3.
Small Wonder 5 can be built once the player has Small Wonder 4.
Small Wonder 6 can be built once the player has Small Wonder 5.

Once the player has Small Wonder 6 he or she can build the Bismarck Tower.

The Bismarck Tower is a World Wonder and it will end the game. All the players will have in-game ranking and it's based on score. Please post the final scores on the forum once the game has ended.

[wieder]

All the wonders will need the same tech for building them. This is maybe not 100% realistic but works for the game mechanics. It prevents someone from building all of them at once. And also prevents from building them when they become available and then ending the game without a warning. The required tech is probably Steel unless someone has a better idea?