The proceeding (ePDF) is based on papers presented at the IABSE Symposium Istanbul 2023 on 'Long Span Bridges'. Includes papers on topics ranging from design and construction practices of long-span bridges, new and older bridge designs, operation and maintenance, repair and rehabilitation, seismic retrofitting, and use of digitalisation in bridge engineering, papers presented at the IABSE Symposium Istanbul, 26-28 April 2023, with Keynote Lectures and Session papers.