The city's monuments and temples were plundered, their stones recycled at Tanis and other sites. Abandoned and forgotten, Pi-Ramesse remained lost in the desert sand for thousands of years.
Today nothing of the city's glorious past can be found at the surface. However, its monumental remains have been identified through magnetic measurements. These can detect the differences in the magnetic susceptibility of various materials in the ground.
"Therefore we are able to detect walls, especially those made of mud bricks," Franzmeier said.
A major investigation was carried out between 1996 and 2012 by geophysicist Helmut Becker and colleagues at the Bavarian State Office for the Preservation of Monuments. The team conducted an extensive survey covering about 1 square mile - one of the largest such surveys ever carried out in archaeology.
Among the features recorded was the building complex excavated by Franzmeier's team. Measuring about 820 by 490 feet, the structure is similar in size to the funerary temple, known as the Ramesseum, which was dedicated to Ramesses II in Thebes, "The layout of the central part definitely resembles a temple," Franzmeier said.
RELATED: Is There a Secret Chamber in King Tut's Tomb? A Final Hunt Will Investigate
The reason for the children's presence remains a mystery. Although no modern concept of banning child labor was in place, the footprints seem to be too small even for children who may have been working.
On the other hand, it appears unlikely that royal kids were left to play in the mud and mortar.
In the next season Franzmeier's team will excavate more of the area and larger parts of the mortar pit, which has only been partially cleaned.
"We are planning to involve specialists which would analyze the footprints and will hopefully find out a little more," Franzmeier said.
The pit where the prints were found was also filled with smashed pieces of painted wall plaster. Unfortunately, most fragments are very small, so no motifs were recognized.
"Nonetheless the strokes suggest that we are dealing not just with different zones of color, but most probably polychrome figural representations," Franzmeier said.
The colors identified so far are black, yellow, red and different shades of blue.
"As they are found within the mortar pit, thus representing debris, we do not yet know exactly where they came from," Franzmeier said. "But it might well be a good guess that they came from one of the walls of the monumental building complex."
WATCH: We Finally Know How the Pyramids Were Made