One of Starfleet's oldest agencies, the Corps of Engineers designs, builds and adapts technology and installations, and enjoys a reputation for ingenuity that reaches even the Dominion's Vorta field commanders.
The Starfleet Corps of Engineers is the service's dedicated engineering arm, with roots in the pre-Federation United Earth Starfleet. A directory seen in the Enterprise episode Demons places its offices at the Fleet Operations Center in San Francisco.
In Star Trek II: The Wrath of Khan the Corps is credited with hollowing out the Regula planetoid for the second stage of the Genesis Project. In the Deep Space Nine episode Rocks and Shoals the Vorta Keevan admits that Starfleet engineers are famed for improvising miracles from almost nothing.
The alternate timeline of Voyager's Non Sequitur has Harry Kim working for the Corps as a starship designer, and in Friendship One Janeway wishes she had its resources to clean a poisoned planet. Discovery's Brother shows the Corps assessing the damaged Enterprise for Captain Pike.