The X‐ray Large Array (XLA) was a concept for a very large area array of proportional counters attached to the Space Station, as the station concept existed in the 1980s and into the early 1990s. It was nominally 100 m2of proportional counters for 0.25–25 keV which was (optionally) supplemented by a coded aperture telescope of area 1–2 m2. Although it never flew, it underwent a pre‐Phase A study at NASA‐MSFC and was discussed at many scientific conferences. The purpose of this presentation is to review lessons learned from the XLA experience, both good and bad. It reviews the scientific rationale and engineering issues in achieving and operating very large X‐ray collecting apertures in space, with updates on those issues in the light of later developments. © 2004 American Institute of Physics