The Fortress Entrance is a Gate introduced in the 12.0.0 update.
It appears to be a decently large stone brick gate with two torches placed symmetrically and nearly to the doorway, there are two columns with a bigger top on each column and there are two blue shield symbols on the columns.
It is used to greatly increase the chance of a higher rocket jump.
- Despite it being categorized as "buildings", it is actually used to prevent access to a building without authority.
- A bigger and a very similar version of the Fortress Entrance can be found in Two Castles.
- It looks like an upgrade to the Stone Gate.