Professor Guy Houlsby on "An Early Structural Engineering Problem: the Oxford Connection". The lecture followed the history of a structure often known as a "Serlio Frame" from its earliest mention (around 1270) to modern times. The structure is an intriguing "reciprocal frame" that is able to span a space with beams that are all shorter than the span required. The rare examples of construction of the frame were discussed (including one in Oxford).