Cielu Castle (pronounced see-AY-loo), often written as Замъкът на небето, is the administrative center of the city of Nova Cielos in the State of Tabatín. The castle was originally a strategically located wooden fortaleza established as Fortaleza Burradurica by Tugali merchants who later were supplanted by raiders after the start of the Tugali War of Unification. The establishment was destroyed after the Новото селище crashed inside the North White River Delta and Undra Aeruma took note of its location, dispatching a small number of troops to eliminate the presence. Once the Tugali raiders had been killed, Aeruma ordered the fort razed. He later returned to the site after the Battle of Taba and elected the construction of a castle from baked delta clay, which forced the deforestation of the local jungle and gave room for Aeruma's planned city.

Until Nova Cielos was completely created, the new Cielu Castle served as an outpost that worked to intercept Tugali and Kiamziati traders coming from the north to prevent the resources from reaching the city of Taba (and, by extension, New Karalla, the capital of the Turnipion Union).