With the intent to wipe out the Gaulish village by any means necessary, Caesar concocts a plan to absorb the villagers into Roman culture by having an estate built next to the village to start a new Roman colony. The colony is to be called the Mansions of the Gods.
The project is led by the architect Squaronthehypotenus. He begins by getting an army of slaves of various races and countries to pull down the trees in the forest. With the help of Getafix's magic, Asterix and Obelix sabotage the plan by planting instant-growth trees, magically enhanced by one of druid Getafix's potions, thus repairing the damage. Obsessed with getting the work done, an increasingly erratic Squaronthehypotenus threatens to work the slaves to death. Taking this remark literally, Asterix gives them magic potion with which to fight back.
Although the slaves are given magic potion in order to rise up, they do not stop work and leave, as Asterix intended. Instead they insist on better working conditions, regular pay and being freed with the consent of their masters after completing the first building of the Mansions of the Gods (the negotiations seem similar to that of modern-day employers and trade unionists). Upon hearing that the slaves are getting better pay than they are, the Roman legionaries also go on strike demanding similar and better conditions for themselves (a common occurrence among French strikers). Since the freedom of the slaves depends on constructing at least one building, the Gauls allow the work to proceed.
Finally, the first building of the Mansions of the Gods is built and inhabited by Roman families. These Romans then go shopping at the village which, before too long, turns into a market town with the inhabitants opening a variety of shops to cater to the Romans. In addition, they start to engage in price wars, literally since there is an actual fist-fight over the issue. The villagers are in disunion and some are adapting to Roman ways, which was Caesar's intention.
Bashing Roman soldiers is one thing, but Getafix insists that civilians are not to be attacked since they are in fact innocent pawns in Caesar's scheme. Thus Asterix comes up with an alternative plan to get the Romans to leave. A couple are shopping in the village when Obelix suddenly rushes at them roaring like a huge monster and apparently threatening to tear them apart. Fortunately Asterix is there to hold him back and explains to the terrified Romans that it is typical "barbarian" behaviour. In fact, Obelix is just putting on an act (courtesy of watching Dogmatix when the little dog is in a bad temper). Asterix visits the couple's apartment that same evening to let them know that Obelix has gotten loose and is coming to see them. This is enough for the terrified husband and the next day the couple leave and return to Rome.
No sooner have they gone that Asterix arranges for Cacofonix the bard to move into the vacated apartment. As a result of the bard's night-time practising, the rest of the Roman inhabitants are quick to leave and return to Rome as well. Squaronthehypotenus tries to keep the place in business by bringing the local Roman soldiers in as tenants, and naturally expels Cacofonix from the building. The Gauls take this as an insult to their pride and bring the building down to the ground.
The Mansion of the Gods is no more and Squaronthehypotenus goes to Egypt to build pyramids in the desert. That evening the Gauls hold their usual celebratory banquet (in which Cacofonix takes part) and the ruins of the mansion ending up as picturesque parts of the woodland.
The book represents a particularly potent satire of 1970s France. Following the explosive riots of May 1968, Goscinny took Asterix in a direction with increasing content referring to current political events in France. This album represents both his dig against technocracy (the young urban planner), the gigantic "villes nouvelles" (new cities) of high-rises which were being created around Paris and especially advertising — the promotion of the Mansions of the Gods which reads like a parody of soon-to-be erected golden real estate investment opportunity.
- At the beginning of the story, Caesar describes to his associates the defeat of Vercingetorix: the Gaulish chief is shown kneeling and pleading before Caesar. The Roman dictator does not appear to want to reveal what really happened. Other Asterix adventures (Asterix the Gaul and Asterix and the Chieftain's Shield) show the bold and proud Vercingetorix throwing his weapons at (that is, literally on to) the feet of Caesar, making him scream in pain.
- Squaronthehypotenus' drive-in amphitheatre for chariots is based on the drive-in theater.
- The quizmaster in the Circus Maximus who coerces the reluctant winner to accept his prize is a caricature of the French television entertainer Guy Lux.
- When all the slaves sing during work, a short, moustached Lusitanian (ancestor of the Portuguese) asks if he could claim a poem instead. This character is likely a reference to the Portuguese poet Fernando Pessoa.