Five-sided building which is the headquarters of the United States Department of Defense.
Located in Arlington, Virginia, just outside Washington, DC, the Pentagon famously has 17.5 miles of corridors [Wikipedia]. Maxwell Smart recalls a CONTROL agent who was so confused he was lost inside for three days. (It turned out that the agent was himself.) [Episode #22: "Smart the Assassin" and Movie: "The Nude Bomb".]
Max poses as disturbed officer Colonel Smart of the Pentagon's Special Weapons Branch while investigating psychiatrist Dr. Myron Braam. The Chief uses the name General McFarland but it is not clear whether this is the identity of a real Pentagon officer or a name the Chief has made up [Episode #20: "All in the Mind"].
CONTROL works with the Pentagon when investigating the destruction of government buildings put up by the Jericho Construction Company. When Agent Charlie Watkins saves Max's life during the case, the Pentagon decides to award him a medal [Episode #52: "Smart Fit the Battle of Jericho"].
The Pentagon appears to have some authority over CONTROL as they order the Chief to hand-pick two agents to locate and destroy KAOS missile base in the Sahara desert. Since the base is underground they cannot use bombers [Episode #56: "Appointment in Sahara"]. He also requires Pentagon approval of an undercover plan at the Roman Baths [[Episode #134: "Smartacus"]. On the other hand, the Pentagon also receives signed orders from the Chief [Episode #111: "The Not-So-Great Escape, Part 1"].
The Chief also attends an emergency meeting at the Pentagon whose purpose is not revealed [Episode #97: "The Farkas Fracas"]. Conversely, the Chiefs of Staff are called to CONTROL to discuss the attack by the Red Feathers Indian tribe [Episode #6: "Washington 4, Indians 3"].
When Max and the Chief are snowed in in Miami, Agent 99 reports to the Pentagon when she and CIA Agent Quigley are assigned to investigate the unusual meteorological phenomenon [Episode #125: "Ice Station Siegfried"
The Pentagon has been targeted for destruction by KAOS on a number of occasions [Episode #16: "Double Agent", Episode #17: "Kisses for KAOS", Episode #102: "The Day They Raided the Knights"] but they have never succeeded. Indeed, when Siegfried commandeers one of Albert Pfister's "kamikaze" pigeons for the purpose it ends up destroying KAOS's own headquarters instead! [Episode #82: "Spy, Spy, Birdie".]
Nurseryman Algernon De Grasse, however, does get one of his bugged plants into the Pentagon's War Room before his scheme is discovered [Episode #135: "What's It All About, Algie?"] and the scientist called "The Brain" was able to sabotage its computer system during his lunch break [GS95 Episode #3: "Goodbye Ms. Chip"].