Once the Fellowship has upgraded to Age 3, its hobbits will be able to build an Edoras Town Centre.  This building will allow you to form an alliance with the Rohirrim by training Theoden and Eomer, as well as gaining access to the Rohirrim cavlary and infantry improvement technologies.  The Edoras Town Centre is where you train Captains and Marshall of Rohan.  Invoking the Last Alliance of Elves and Men, from the Edoras Town Centre will result in Galadriel sending you her captain - Haldir.

