A Sihakona, also known as a Sith Castle or Sith Manor, is a castle, manor or any other edifice built by and/or for the Sihak.
Usually when people talk about the Sihakona, it's in referrence to the main one: one of the castles built during the unification around the bender capital, ... . It was built to represent the Royal House of the Sihak -- the Sith. It was one of the first to be built and as thus is one of the most remote ones. Many of the original constructions started to serve other purposes but as the Sith are a wide family, that building still serves as their headquarters.