Despite the appearance of permanence that historic buildings create, many if not most of the worlds famous cities have been almost entirely destroyed either by war, property speculation or Ayn Randian architects. They have been rebuilt, either as replicas (Warsaw) or even in the image of the culture that destroyed them (Hiroshima). Here are images where either we or others have matched up locations for incredible before and after shots.

Kowloon Walled City (KWC) was a 10-16 storey monolithic 6.5 acre city block in the flight path of the old Hong Kong airport, that housed somewhere between 35,000 and 50,000 people when it was finally demolished in 1993. 30 times the density of Manhattan with no streets and little daylight, it was a rat infested, cockroach ridden filthy labyrinth. KWC was a no-man's land that fell neither under British Jurisdiction nor Chinese, where Hong Kong's appetites for the 3 vices: prostitution drugs and gambling could be satiated, but where ordinary families lived alongside nearly 800 factories and shops. It had 161 unregulated doctors and dentists along with food producers from whole pig roasters to the suppliers of most of Hong Kong's fish balls. Most of the people that lived in KWC never left.Dozens of sites have covered KWC before (as have we), but its such a strange and unusual Oobject that we've trawled through hundreds of sites to try a pull together a list of our favorite images and links which succinctly describe it.

Tokyo flash became famous for selling amazingly abstract watches which told the time in any way imaginable from Morse Code to a video game display.Here are some of their classics along with any other amazing Japanese watches that we find.

A gallery of products using radioactive materials.Because radiation was seen to be new and powerful, at the beginning of the 20th century radioactive material was used in products such as face creams, mineral water and medicine, by equating power with rejuvenation. For similar reasons it was even used in items from spark plugs to condoms. Although many of these items are from an age when the dangers of radiation were not known, radiation is obviously useful as a healing tool for cancer therapy, but it is still used in legal Chinese remedies, which are respected more because of their age rather than efficacy and quack homeopathic medicines which are tolerated while unproven, because they are harmless water.Vote on your fave examples.

P.J. O’Rourke observed that when someone digs up Manhattan in 2000 years, they’ll wonder what kind of hideous torture the civilization inflicted on people there because of the amount of gym equipment. The same could be said of this stuff which, despite its bizarre appearance, is generally quite benign.Most interestingly, these devices were the work or Dr Kellog, now better known for his breakfast cereals which were part of his health regimen as medical head of the Battle Creek sanitarium.A big thank you to John EverBlest at Healthexhibits.com who provided me with these pictures from his wonderful collection.

There is a strange beauty to slow motion videos of car crash test dummies and airbag deployment, but these don't compare to the similar, but far more extreme safety measure of a fighter jet ejection. Here are videos of various aspects of their deployment testing and training. Some of these are absolutely mesmerizing.

A gallery of some of the most impressive control rooms, including the original NASA mission control, the Beatles recording studio, the NORAD nuclear war room, what is left of Chernobyl reactor 4 control and control rooms for TV, traffic, subways and particle accelerators.

I deliberately picked spiral ramps as opposed to spiral staircases, since they include buildings whose entire form is determined by the ramp rather than being merely a feature. Examples include everything from the Guggenheim to the Reichstag, the Tatlin Tower, Lingotto Factory or Lubetkin’s brilliant Penguin Pool at London Zoo. My personal favorite is the spiral ramp at Convair Aeronautics, by Pereira and Luckman, the people that designed the now defunct control tower at LAX. The insane but amazing proposal for a half mile high drive up skyscraper for the 1937 Paris exhibition is one example of a spiral ramp car park, and I’ve thrown a few examples of anonymous car park ramps into the mix to show how beautifu these often overlooked pieces of background architecture are.

Todays welding is a long way removed from the video included here of forge welding at the beginning of the 20th century., where dissimilar metals were headed and beaten together with hammers. State of the art robotic welding machines can perform an intricate ballet of hi tech gadgety bravado, including the incredible remote welders which are shown spot welding materials several feet away, with laser beams.

Being slightly anally retentive about this list, I’ve limited it to pictures of the actual typewriters that were used by 9 famous writers, not just examples of the same model. Included are James Bond creator Ian Flemming’s gold plated portable that would have been worthy of Goldfinger himself, and the typewriter used by Apple Mac user, Douglas Adams, to write the Hitchhikers Guide, before there were such things as Apple Macs.

Babel is interesting because it represents the ultimate in imaginary architecture, a skyscraper of the mind. The Tower of Babel is the archetypal image of a giant tower, a man made hill, yet nothing like our idea of it has ever been built. The closest are possibly Mont Saint-Michel or perhaps the downtown Manhattan cluster, yet one is a natural mound and the other an apparent hill created from many buildings.The idea of Babel traces back to ancient Sumerian stories from the time of 5000 year old Mesopotamian Ziggurats, to the reinterpretation of these myths in the book of Genesis. In the 16th century the ironic obsession with Babel among 16th century painters in hill-less Lowland Europe, created the most well known imagery, but it evolved further with the unbuilt Palace of the Soviets or the imaginary babel in the retro futuristic skyscraper cities of Fritz Lang's Metropolis.

Several star architects such as Herzog and de Meuron and Rem Koolhaas have produced building designs that have jutting out and cantilevered components that give the overall impression of a giant game of Jenga. The New Museum on the Bowery in New York, is the latest addition to this genre of minimalist deconstruction. But the most interesting Jenga building is an obscure, former Soviet ministry in Georgia, which is quite mad.

The most claustrophobic places in the world. Imagine sleeping in a space smaller that a jail cell, deep under water, with a very large live bomb. This is what the business ends of submarines look like. Brass or steel hatches, like the eyes of a metal insect, peer out on a tiny Jules Verne-like space covered in buttons, gauges and levers, which often contains bunks right next to the torpedos themselves. Torpedo rooms are one of the strangest man made spaces on earth, or rather below it.

A perfect example of nothing dating like the future, the garbage can robot is a retro-futuristic cultural icon. Some of these were cheap props for cheap movies, but others were serious visions of the future. If nothing else they demonstrate quite how imaginative the Metropolis robot that stands the test of time was.

As people blow each other to pieces, daily, on the planet below, the silently floating Hubble telescope seems to represent everything great about humankind. Here are our other favorite telescopes.Update: Have been in continuous operation since 1963, the Arecibo project is in danger of closing due to cuts in funding. Jonathan, who is a researcher working at the Arecibo dish has posted a link in the comments to its website where you can donate or voice your support. http://www.arecibo-observatory.org

If there was one cassette deck to own, it was a Nakamichi. With the release of the model 1000 (its number reflected its high price) in the early 70s, reel-to-reel tape recorders were rendered all but obsolete, for consumers. With the release of the 700 Nakamichi created a functional and design classic.Because cassette tapes are in the gap between vintage retro and mere obsolescence, Nakamichis can be picked up for a reasonable price on Ebay.

Manikins (the alternate spelling, mannequin, is usually used for the store window variety) which are used for medical training are extremely interesting devices with accurate and working anatomical elements. This list is larger than usual since the number of interesting items meant that we kept on looking.