The Towers are distributed over the 4 Sectors of Lyoko, at the rate of 10 towers by Surface Sectors. In the episode 49 «Franz Hopper», we discover a 41st one, in the Sector 5.
On the Replikas, we have no informations about the number of towers, in none episode. Yet, since the Sector contained in a Replika is an exact copy of the Lyoko model, it isn't stupid to think that an alternate world managed by XANA contains 10 towers (and one for Carthage's Replikas).
Each tower looks like a giant pillar which the base looks a little bit like a trunk. They are white and are illuminated with a glimmer whose the color changes according to who uses them.
-If the tower is deactivated or used by Aelita, it is blue. We mostly say in that case that it is deactivated, which is a vocabulary mistake, given that Aelita can, too, act in the landed networks from the towers. She does it in the episode 24 «Ghost Channel» to help Jeremy, holded up by Jim and the director.
-When XANA activates a tower to attack our world, it is red.
-When Jeremy activates a tower, it is green.
-When Franz Hopper activates a tower, it becomes white. We must note that at the end of the season 2, Hopper activates all the towers of Lyoko, consequently in the season 3, even when Aelita deactivates a tower, its halo becomes white again and not blue.
The towers which really are deactivated are, in fact, damaged towers : They lost then any halo. Their datas bases are damaged and they need time to regenerate. It happens when XANA hits, with the help of the powerful shots from the Megatanks. It can also happen if the power cables of the Tower are broken.
The inside of the towers is still the same, independently of who uses them. We can enter by any side but we don't always land on the main platform inside. Odd and Ulrich experiences it and fall at the bottom of the Tower in «XANA Awakens» In the towers, the walls are covered with lines of binary datas. There are two platforms, where appears the eye of XANA : one at the level of the ground, another higher. It gives access to an interface which permits to anyone, on Lyoko or a Replika, to get to the real world. This interface is also the heart of the tower and it's by this one that the tower can change of owner or that the programs, like the one generating the Replikas (Episode 67 «Double Take») work.
Finally, remark that the towers are not always right in the middle of a desert platform. Some of them are well hidden in virtual people's eyes. However, this point isn't tackled here. In the page of each Sector, we indicate the particular towers which added some suspense in an episode where they appeared. So visit the pages of the Sectors to collect these informations.
Desert Sector – Forest Sector – Sector 5 – Mountain Sector – Ice Sector (Liens vers les pages concernant chaque territoire)
The towers are datas banks which tirelessly searches the terrestrial networks looking for informations and energy. As they are linked to these networks, they can act there and so represent, with scanners, the only bridge between Lyoko and Earth.
The tower are used to create a link with Earth but also to execute computer actions asking a lot of energy like rematerialize Jeremy, stuck between two worlds (Episode 19 «Frontier») or also to decrypt the diary of Franz Hopper (Episode 51 «Revelation») !
Linked to Carthage, they send all the datas collected by the latter. They can also receive energy coming from this Sector.
We can also suppose that the towers are in connection with the center of Carthage : the Core of Lyoko. It explains that with the typing of a certain code in the Way Towers, we can irreparably destroy a Surface Sector.
The towers of Lyoko are classifiable in three kinds.
The archetype is the classic tower. 8 towers out of 10 of a Sector are concerned and they communicate each other. It means that, if you enter in a tower and you throw yourself in the flux of datas, you will be directly moved to another tower. As the flux of datas are one-way, if you fall in the flux of datas of a tower, you won't be moved to the tower you were coming from but to another tower, and so on to the 8th tower which will get you back to the first tower you used at the beginning.
The two last towers are very particular. The first and the most important one is the Way Tower. In addition to be the main tower of the Sector, this one will allow you to leave it and to reach another Sector. In clear, its flux of datas doesn't match with another tower of the Sector you are but with the tower of a bordering Sector.
The last tower is just the arrival tower. It means that it's the tower where you will land in the Sector if you take the Way Tower of another Sector.
Before concluding this characterization of the 10 towers of a Sector, a warning is essential. The concept of the Towers doesn't seem to be clearly defined by the writers and shows some defaults.
On one hand, the concrete informations about the Towers are few and squandered in the episodes, on the other hand, at the level of the making, there seems to have some blunders as for the representation of the towers.
The information saying that the «non-way towers» communicate each others between the different points of the Surface Sectors has been showed in the episode 72 «Crash Course», namely very lately in the series.
To give yoy an example, the Sectors doesn't always seem to have the same Way Tower. Especially the Ice Sector. When Xanatified Aelita will want to destroy the Ice Sector, she won't target the same Way Tower (Episode 59 «The Secret») that the one Aelita will finally use to destroy the Ice Sector in the episode 61 «Sabotage».
This same tower of the episode 61 seems to be at the same time the Way Tower and the arrival Tower of the Ice Sector. Indeed, in the prologue, when Odd and Ulrich pass (or rather wallow) by the Way Tower of the Forest Sector, they come out onto the Ice Sector by this tower.
From then on, other theories can be envisaged. The Surface Sectors can have two Way Towers which can also be arrival Towers.
The point which maintains that theory is that each Surface Sector is linked to two others Sectors, so having two Way Towers is a priori logical.
What undermines this idea, it's that the lines of the heroes always imply that there's only one Way Tower per Sector. The episode 19 «Frontier» also totally contradicts this idea. In this last, Aelita goes all over the 4 Surface Sectors to collect the energy of the Way Towers. When she's over with a tower, she jumps in its flux of datas, reaches another Sector … and goes to the Tower of the Sector said. But if the arrival towers were also Way Towers, Aelita wouldn't need to move into a new tower , not even once…
No certainty and mistakes on that subject, so …
However, inside the Digital World itself, the tower represent, if we can say so, the urban network. It means they occupy an important part of the flow network and the communication network.
To use a (lame) comparison :
-The large areas of Lyoko represent at the same time the roads and the sidewalks, where the Lyoko-warriors walk and use their vehicles.
-The common towers represent the high speed train which links at high speed the different points of only one Sector.
-The Way Towers, with the Transport Orb, are the airports which link one Sector to another.
In the categories named higher, Carthage's tower seems unclassifiable. We ignore the effects it would have if someone types the code of the Destruction of Sectors. Carthage doesn't have Way Tower and can only be reached by the Transport Orb or by the codes of direct materialization.
However, when the tunnels of the celestial vault are opened, the heroes sometimes go out there by the Way Towers of the Surface Sectors ! The opposite manœuvre seems impossible…
The Replikas don't have Way Towers or arrival towers, because the Sectors they contain are alone and communicate with no other. There are only normal towers.