The lowering the "keystone" into place at the reconstruction of the arches at the archaeological site of Thyatira in modern Akhisar.
The metal framework is called "centering." This type of framework was used in ancient times—only of wood—to build arches. In ancient times they were not constructed at ground level but on top of columns. Thus the centering was much more elaborate and wooden scaffolding was used for the workmen to stand on. In ancient times they also used cranes that were powered by people, with ropes and pulleys!
This picture was taken in May 2019. The plans are for a major upgrade to the archaeological park.