Lost Thresholds: The Erosion of Architectural Language and its Consequences for Sensory Orientation Part 2 Dissertation 2026 Cáelan MacTavish Queen's University Belfast | UK Architecture is communication. It speaks through light, material, sound, enclosure, and sequence, helping us understand where we are and when one condition has given way to another. For much of human history, thresholds formed part of that language. They marked passages between worlds, gathered meaning around the act of crossing, and prepared the body for change.Lost Thresholds begins from the suspicion that this language has begun to fade.Through recorded journeys, thresholds are encountered in motion. Not as fixed architectural elements, but as events: felt in the cool of shade, the echo of footsteps, the ripple of cobbles, the compression of a crowd. What emerges is not the disappearance of thresholds, but their dilution. The boundary remains, yet its role changes. Where thresholds once gathered experience, they increasingly manage movement. For those whose experience of space depends upon legible sensory and spatial cues-including neurodivergent and disabled people-the thinning of thresholds is rarely subtle. Yet what appears first at the margins of perception reveals a broader condition. If thresholds help us orient ourselves in the world, what happens when their language begins to fail?What is at stake is not simply the loss of a spatial device, but a way of being in the world. This work asks what happens to architecture--and to us- when the world no longer pauses to let us know we have arrived. Tutor(s) Keith McAllister