U.S. Army Corps of Engineers. The medieval castle is inseparably connected with fortifications and architecture.
http:// www.usace.army.mil/About/History/Historical-Vignettes/General-History/090-Corps-Castle/
65th Eng. Bn. celebrates its birthday
https:// www.army.mil/article/92059/65th_Eng__Bn__celebrates_its_birthday/