Anastylosis is an archaeological term consisting in a reconstruction technique whereby an artefact is restored using the original architectural elements. Experts can sometimes imply months or years to carry out this task counting on their expertise. Software procedures can represent a valid support but several challenges arise when dealing with practical scenarios. This paper starts from the achievements on DAFNE challenge, with a traditional template matching approach which won the third place at the competition, to arrive to discuss the critical issues that make the unsupervised version, the blind digital anastylosis, a hard problem to solve. A preliminary solution supported by experimental results is presented.