Architecturally Exposed Structural Steel (AESS) is seeing increased and widespread use around the world. AESS is steel that is a purposefully expressed part of the architectural design of a building and subject to normal views by pedestrians or occupants of a building. It must simultaneously satisfy aesthetic and structural requirements, hence placing itself strategically to include architecture and engineering. Its use was derived from High Tech Architecture and has come to be part of the mainstream of the use of steel in architectural design. Because it is clearly visible, AESS is subject to closer tolerances than standard steel that is hidden from view, and therefore requires special consideration during the design phase of a project. AESS requires a much higher level of communication between the architect, engineer and fabricator in order to select details that are appropriate to the fi nish, fi re protection system and class of the structure.