To start its construction you need a lot of rss: 1 Billion of Food, Lumber and Stone, 750M of Iron ands 250M of Silver.
The buildings that can be constructed in the stronghold are (in order) The area surrounding the Stronghold is called the Valley of the Aesir. The original size of 12x12 tiles or 144 squares can be extended via upgrades (see House of Jarls). The clan chief can choose to build a Stronghold anywhere on the map that matches the required conditions, but it cannot be moved once placed. SH) was introduced in the game update during December, 2016.