Engineering bay

The engineering bay is a terran building used to improve the quality of weapons and armor fielded by infantry. Within the Dominion Armed Forces, whenever a strike force is deployed planetside, the engineering bay is one of two key research facilities to be established in a field base as soon as possible (the other being the armory).

StarCraft
The engineering bay upgrades the quality of weapons and armor used by terran infantry. It can lift off.

Development
In the StarCraft beta there existed a structure called the weapons plant. Though canceled before the release of the game, it bore resemblance to the engineering bay's structure.

StarCraft II
The engineering bay reappears in StarCraft II. It can no longer lift off. In the Wings of Liberty single player campaign, the Hi-Sec Auto Tracking and Building Armor upgrades are not available, while the Neosteel Frame upgrade to bunkers is an upgrade purchased in the Hyperion's armory.

Co-op Missions
Jim Raynor, Rory Swann, Nova Terra, and Mira Han and Matt Horner have a number of unique upgrades available to them at the engineering bay. Han and Horner's engineering bay does not give them infantry upgrades, but unique upgrades for Mira's units.

Development
The StarCraft II engineering bay was designed to be a more simple structure than its predecessor. It was decided to make it a grounded structure as per the belief that only unit-producing structures should be able to lift off.