An intact mosaic from Late Antiquity discovered during restoration of a historic municipal building in Istanbul is now a floor again, covered in plexiglass and welcoming visitors to the new Zeytinburnu Mosaic Museum.Visitors of Turkeys newest museum move across elevated glass walkways, suspended right above the original floors themselves. The mosaics are not relocated fragments mounted on walls, but surfaces that remain exactly where they were first laid, preserving their context for all to see.Beyond the floors, the museum presents terracotta vessels, coins from various centuries and the marble sarcophagus discovered on site. With its library and exhibition spaces too, the institution is more than one archaeological stop, it forms part of a broader cultural revitalisation in Zeytinburnu.The 190-square-meter (2,045 square feet) mosaic floor was discovered in 2015 when the Ottoman-era military hospital building from 1893 was being converted into an art center. The decorative patterns of stars, geometric knots, polygonal shapes, and florals date the mosaic to fourth or fifth centuries. It was likely installed in a suburban Roman villa, as the location was outside the ancient walls of Constantinople.All construction was suspended and a systematic archaeological excavation ensued. In addition to the full mosaic, a subsequent excavation in 2019 uncovered a marble sarcophagus containing the skeletal remains of two people, a brick tomb, terracotta vases and coins. These finds date to different periods, attesting to use of the site over centuries long after the floor was made.Turkey has an enormous patrimony of Roman and Byzantine mosaics, and there are currently eight museums in the country dedicated to displaying these masterpieces of ancient art. What distinguishes the Zeytinburnu Mosaic Museum from ones like the Hatay Archaeological Museum, famous for a collection of ancient mosaics of unparalleled variety and quality, is that its mosaic has been left in situ instead of being removed, conserved and reinstalled in an exhibition space. The only comparable treatment is in a hotel that has become an accidental museum now by virtue of the fact that the worlds largest mosaic, a dazzling tour-de-force of geometric patterns and psychedelic floor undulations, was discovered there during construction.