Hall of Court (Old) is a hidden file found within the SDK. It is an earlier version of the Hall of Court level, and is located at UDKGame\Content\Maps\DD_Lev_05_Old.udk within the "Dungeon Defenders" directory, if the Dungeon Defenders Source Development Kit has been downloaded.
While the map contains the usual polish one would expect from a Dungeon Defenders level, it lacks a roof/skybox.
This is in indoor version of the Hall of Court map, with visual elements of The Throne Room (Red and Blue carpet on opposite sides, various textures). This is also presumably why the map was reworked into the current version, as no two maps are alike visually with the exception of this map and the Throne Room.
In terms of layout, the level is virtually the same, with a minor difference being an elevated pathway and guard rail on the north-eastern and south-eastern sides of the map. This would prevent ranged monsters pooling into the middle and attacking the crystal, which often occurs in the present Hall of Court level.