While it's true that the walls protect the citizens from titans, it is speculated that "Attack on Titan" season 2 may reveal that these are actually chaos waiting to happen as the walls may have titans hibernating beneath the surface.
According to the latest reports, there are various theories suggesting that there are several titans buried inside the walls. This means that the walls can pose a threat to the humans of "Attack on Titan" universe and cause the collapse of mankind on the said anime series.
However, the mentioned plot may be more than just a theory as, after all, the season 1 finale episode of "Attack on Titan" left a cliffhanger scene showing that a titan is, indeed, buried beneath the surface of the walls. Furthermore, there are several online forums where those who have already read the manga version of the anime series reveal that the walls are, indeed, made of titans.
One participant in an Anime Stack Exchange forum, for instance, revealed that the walls are made of a special type of titans that look like Colossal Titan. According to the information of the incognito source in the said forum, it was the first King on "Attack on Titan" who used his Coordinate power to compel the said titans to use their hardening power to give shape to the walls. The same king is said to be also responsible for erasing the memories of the titans to the humans after the walls have been built and created the Wallist Church to help him oversee that the walls remain safe.
Based on the first released trailer for "Attack on Titan" season 2, it is suspected that the upcoming season of the anime will fuse two story arcs from the manga: The "Clash of Titans" and "Uprising" story arcs. However, it is also speculated that the highly anticipated season will finally unveil the history of the walls as the second preview of "Attack on Titan" season 2 seems to suggest so.
Will "Attack on Titan" season 2 finally unveil the history of the walls? Are they really made of a special type of titans?
Find out when "Attack on Titan" season 2 arrives this April.