Criticism: Where are the fortified cities?
Response: I've seen several fortified cities, well, the ruins of them anyways. Just go on any Mexican (see: Becan) or Guatemalan ruins tour and you'll see plenty of fortifications, or what is left of them.
For example, I visited the ruins of Zacaleu, which dates back to between AD 250–600 and is just outside of Huehuetenango in Guatemala. The very first thing that impressed me about it was the defensive earthworks in the form of a gigantic moat dug around the entire complex. It was definitely not a natural formation for that area and it would have been a formidable obstacle to invaders. The entire site was also once fortified with walls. It was so impenetrable that it caused Spanish conquistador Gonzalo de Alvarado y Chávez to need to lay siege to it for months, having to wait for its occupants to starve to death.
Bishop Las Casas, when in Mesoamerica, reported in his Apologéitca Historia that he saw "towns enclosed by very deep moats...with marvelous buildings of stone masonry of which I saw many." In that one statement, he described both the earthworks AND the masonry (which inevitably involves some kind of cement).
The Popol Vuh describes the palisades, much like what we find in the Book of Mormon:
...having talked together, they built a wall at the edge of the town and enclosed it with boards and thorns. Then they made figures in the form of men, and put them in rows on the wall, armed them with shields and arrows and adorned them, putting metal crowns on their heads. These they put on the simple wooden figures, they adorned them with the metal which they had taken from the tribes on the road and with them they decorated the figures.
See The Popol Vuh, pg. 157.
They made a moat around the town, and then they asked advice of Tohil [their god]: 'Shall they kill us? Shall they overcome us?' their hearts said to Tohil [prayer for revelatory guidance before a battle being a common theme of the Book of Mormon].