A five sided polygon with angles adding up to 540o (degrees). The area of a regular pentagon is 1.721s2, where s is the length of a side.

The perimeter for a regular polyhedron is s*n where s is the length of a side and n is the number of sides.

Pentagons are very polite unless you insult them.

Geometric shapes

. .
. .

Is this a pentagon?

Those biased by the Aneristic Illusion would say Yes. Those biased by the Eristic Illusion would say No. Criss-cross them and it is a star.

An Illuminated Mind can see all of these, yet he does not insist that any one is really True, or that none at all is True. Stars, and pentagons, and disorder are all his creations and he may do with them as he wishes. Indeed, even so the concept of number 5.

The real reality is there, but everything you KNOW about "it" is in your mind and yours to do with as you like. Conceptualization is an art, and YOU ARE THE ARTIST.

Convictions cause convicts.

--Principia Discordia, Hypertext version, accessed Prickle-Prickle 36 Discord, 3166.

The Pentagon is the headquarters of the United States Department of Defense, located in Washington, D.C. It's one of the largest office buildings in the world, with an outside perimeter almost a mile long and containing 17.5 miles of corridors which are walked by some 26,000 employees and personnel. But it's also one of the most efficiently-designed -- any two points within the building are no more than a seven-minute walk apart.

It was conceived in mid-July 1941, and built with astonishing speed. Groundbreaking took place on September 11 of that year, and construction was completed just sixteen months later. Its size allowed it to replace a total of seventeen pre-existing War Department buildings and connect them far more efficiently. It was built with fifteen miles of pneumatic tubes for mail delivery, which are actually still used today.

Of course, it's secure. But no security is perfect, and the DoD knows that they're one of the biggest targets in D.C. or the country. The Pentagon Building Security and Emergency Procedures Guide is a twenty-two page handout briefing Department employees on subjects from rules regarding visitors and security passes, to how to recognize a possible mail bomb that slipped through screening, to how to deal with a possible hostage situation in your area. The last page includes a checklist of things to ask a caller if your phone rings with a bomb threat.

I'd hate to be the guy responsible for maintaining their firewall.

A station of the D.C. Metro system.

General Information
Lines: Blue, Yellow
Address: Patton Circle and Marshall Drive, Arlington, VA
Location: Pentagon Shopping Concourse
Parking: None.
Opened: July 1, 1977

Last Trains
Franconia-Springfield, weekdays: 12:21am
Franconia-Springfield, weekends: 2:21am
Addison Road-Seat Pleasant, weekdays: 11:52pm
Addison Road-Seat Pleasant, weekends: 1:52am
Huntington, weekdays: 12:05am
Huntington, weekends: 2:05am
Mount Vernon Square / 7th Street-Convention Center, weekdays: 11:49pm
Mount Vernon Square / 7th Street-Convention Center, weekends: 1:49am

Bus Lines
Metrobus: 7A, 7B, 7C, 7D, 7E, 7H, 7P, 7W, 7X, 8S, 8W, 8X, 8Z, 9A, 9E, 10A, 10E, 13A, 13B, 13F, 13G, 16A, 16B, 16C, 16D, 16E, 16F, 16G, 16J, 16L, 16S, 16U, 16W, 16X, 17A, 17B, 17F, 17M, 17G, 17H, 17K, 17L, 18E, 18F, 18G, 18H, 18J, 18P, 21A, 21B, 21C, 21D, 21F, 22A, 22B, 22C, 22F, 24M, 24P, 25A, 25F, 25G, 25J, 25P, 25R, 28F, 28G, 29C, 29E, 29G, 29H, 29X, P13
Fairfax Connector: 306, 383, 384, 385, 989

Serves, perhaps too obviously, the U.S. Pentagon.

From here you can...
go back to the Metro project,
jump to the yellow or blue line,
go inbound to Arlington Cemetery or L'Enfant Plaza,
or outbound to Pentagon City.

Inner Sphere Classified Files: The Pentagon


Another Pentagon is the set of five planets orbiting a sun in the Outer Rim, shaped (obviously) in a Pentagon, in the Battletech/Mechwarrior saga. In 2784, a political fracture caused the Exodus, where the Star Leauge Defence Force left the Inner Sphere, as well as many small groups that left for the Periphery Realms. The Clans departed in search of a galaxy similar to the Inner Sphere, and stumbled upon the Pentagon. Here they set up their militaristic lifestyle in the traditon of the Star League, under the leadership of Aleksandr Kerensky. This did not last, however, as in Human tradition the worlds splintered and violent war broke out. Alexander's son, Nicholas Kerensky, left with 800 of his most loyal commanders to travel deeper into unknown space and settled elsewhere in the Outer Rim where they established the Clans. The Pentagon worlds were ravaged by the wars, and their inhabitants eventually ended either returning to the Inner Sphere or drifting off in search of the Clans. Few of the Pentagon's inhabitants survived.

A few more factoids regarding The Pentagon (the U.S. DoD version). The construction project that built it was headed by Gen. Leslie Groves, whose next assignment was to run The Manhattan Project - the massive effort to produce the first atomic weapon.

The recent attack on the Pentagon brought to light (in an unfortunate way) some additional tidbits of information. For example, the outer wall of the building is constructed using limestone slabs which were all acquired from the same quarry. For the rebuilding effort following the attacks, the same quarry will be supplying matching limestone, and the man in charge of that is a stonecutter whose first job as a teenager was building the original walls for the building.

The Pentagon was in the midst of a massive reconstruction when the attack occurred. This is one reason that there were so few casualties; of the sections that were hit, one had been cleared of personnel to allow work to begin, and the adjoining section's personnel had just begun to move back into their refurbished offices. Another was that the newly-completed areas (the first phase of the reconstruction, three years in the process, was five days from completion on 9/11/01) contained the fruits of the safety engineering done for the reconstruction. Those include blast-resistant windows, metal reinforcement for the outer support walls, modern sprinkler systems and better exit routes. The main damage to the rebuilt wedge was water damage from the sprinkler system.

Prior to the attack, the rebuilding effort had already begun to address the building's vulnerabilities to more mundane threats. The rising popularity of car bombs in the 1960s and 1970s prompted the closing of the auto concourse, which had previously allowed motor vehicles to actually enter a space underneath the outer ring. In the recent work, an annex was built to move all shipping operations out of the building, since up until that point, semi-trailers had regularly backed into the outer ring to discharge cargoes of mail, supplies and whatever. Now, there is a completely separate building which handles all package traffic to the building. Packages are opened, inspected and approved there, some several hundred feet from the main building, and are then transferred to their destinations through an automated underground tunnel to avoid tampering.

City buses, until recently, would routinely stop next to the building, coming within perhaps ten feet of the outer walls. The Khobar Towers and Oklahoma City incidents have prompted changes in traffic patterns to ensure all large vehicles remain a good distance from the building itself. In places, an earth berm is placed between traffic accessways and the building itself for added protection.

On a lighter note, the central courtyard (the building consists of several nested pentagons in order to maximize window space and provide courtyards) contains a cafe where building personnel can enjoy lunch al fresco. The name of the cafe, reflecting the 'privileged' status of the building in the nuclear targeting documents of the world, was (and may still be) the "Ground Zero Cafe."

Seniority can be roughly inferred from the placement of one's office in the building, with more senior officials enjoying exterior views and a shorter walk from entrances.

During the planning phase for the ongoing reconstruction, the first thing that planners did was to decide if, in fact, the three-plus billion dollars (and twenty years) that the reconstruction was projected to cost would be better spent building a replacement, modern facility - one which, in addition to being new, would lie somewhere other than the flight path of National Airport. The requirements for the site included the massive demands the building would place on the local water, power and sewage systems; efficient road access, fifteen thousand parking spaces, and commuter access for the twenty-five thousand plus occupants. Given those parameters, the only realistic site was Fort Belvoir, south of D.C. proper in Virginia.

The problem was that upgrading the facilities there to handle the load, as well as the projected cost of extending one of the regional Metro commuter rail lines to reach the fort, coupled with actual construction costs, would push the project's total cost far over the estimate for the Pentagon reconstruction. Lee Evey, program manager for the reconstruction effort, explained in a briefing on C-SPAN several days following the attacks that these (among others) were the reasons for undertaking the effort required to perform such a massive renovation while the military continued operations in the building. Dubbed 'The Phoenix Project,' the post-9/11 rebuild involves the reclamation and rebuilding of over 400,000 square feet of the building, plus the repair of approximately 1.5 million additional square feet damaged by collapse, fire or water. Completion of the Phoenix Project is scheduled for September 11th, 2002 - one year after the attacks - with full occupancy on that day.

Some final dry facts and figures on the building itself:

  • It is five stories tall, with each face stretching over 900 feet. The total circumference is nearly a mile.
  • It is widely considered to be the largest single building in the world.
  • It was originally built as a 'temporary headquarters' for the Department of Defense, intended to last perhaps fifteen years.
  • The central courtyard is over five acres in size.
  • It was completed (from groundbreaking to completion) in sixteen months from 1941-1942.
  • Until the reconstruction, it had no passenger elevators.
  • The rush nature of the original construction meant that there were no accurate and complete architectural diagrams of the building when the recent rebuild began. The process of planning and executing the rebuild was described as "archaeological architecture" by one participant.
  • The building's five rings are connected by radial corridors; one at each vertex of the pentagon and one in the center of each side. The five sections of the building delineated by the vertex corridors are referred to as 'wedges,' and each is intended to be an independent entity as far as utility feeds, HVAC, etc. (not that it worked out that way in practice, naturally).
  • It has over nineteen miles of corridors.
  • It contains 6.5 million square feet of office space.
  • It was designed so that no point in the building is more than a seven-minute walk from any other.


  • C-SPAN Briefing on the Pentagon Reconstruction: Lee Evey, Program manager. October, 2001.
  • Pentagon Engineers Divide and Conquer. Engineering News-record; Sept. 4th, 2000 issue.
  • PBS online: Rebuilding the Pentagon (http://www.pbs.org/newshour/bb/terrorism/jan-june02/rebuilding_1-16.html)
  • http://www.hnp.org/publications/hnpt_issues/hnpt2002/hnpt0311.htm
  • http://www.vnis.com/vetnews/usdefense/usdefense2002/usdefense2002-011.htm


  1. The floors of the Pentagon are numbered from 1 to 5, and each ring is lettered from A to E (A on the inside).
  2. Because of the steel shortage during World War II, the floors of the Pentagon are connected by huge concrete ramps.
  3. If you take a guided tour of the Pentagon, you will see big stately wood-paneled corridors. Most of the Pentagon is yellowing and rusting, and not all that stately.
  4. The basement of the Pentagon is larger than the Pentagon itself.
  5. The basement has also been altered so many times that it had to be re-surveyed during a recent renovation.
  6. Several large portions of the Pentagon catacombs were built with large amounts of asbestos. Rather than remove it, the Department of Defense elected to brick the areas over, sealing them off until the building was renovated in the mid 1990's.
  7. According to many reports (none of them official), the Pentagon is connected to other key sites in Washington, DC by a network of underground tunnels large enough to accommodate golf cart traffic.
  8. The Pentagon site was originally earmarked for an expansion of Arlington National Cemetery.
  9. While the construction of the Pentagon was being debated in Congress, many congressmen argued that its massive size would no longer be necessary after the war.
  10. Over 1,000 architects worked feverishly in a nearby hangar to supply over 14,000 artisans with blueprints.
  11. All Pentagon employees are given a smoke mask to use in the event of a terrorist attack.
  12. The building has its own federal police force, the Pentagon Force Protection Agency. Before September 11, 2001, security was supplied by military police, and would rotate from branch to branch each week.


The mailing address of the Pentagon is "The Pentagon, Washington, D.C.", even though it is located in Virginia. This is by decree of the USPS, who have assigned six ZIP Codes to the zone: one for each of the four major armed services, one for The Joint Chiefs of Staff, and one for the office of the Secretary.

Pen"ta*gon (?), n. [Gr. ; (see Penta-) + gwni`a angle: cf. L. pentagonium, F. pentagone.] Geom.

A plane figure having five angles, and, consequently, five sides; any figure having five angles.

Regular pentagon, a pentagon in which the angles are all equal, and the sides all equal.


© Webster 1913.

Log in or register to write something here or to contact authors.