The kilometre-high skyscraper, the underwater hotel, the cloud on stilts ... Steve Rose mourns the eye-popping erections that should never have been commissioned

Pundits have been lining up to say "I told you so" over the bursting of Dubai's construction bubble, so now it's my turn. I did tell you so, a year ago. But what now? In architectural terms, Dubai has surely been the story of the decade. We're just not sure if it's a comedy, a tragedy or some surreal, hallucinogenic fairy tale.

On the other hand, the Dubai experiment has undeniably expanded the realms of what it is possible to build. Before the Palm Jumeirah and its ilk, or the World, who would have contemplated works on such a scale? Reclaiming land from the sea is nothing new, but only Dubai had the imagination to make pretty patterns with its coastline, to shape the earth to such a colossal degree that you need Google Earth to appreciate it.

Other countries have evidently been eyeing Dubai's coastline, too. In Russia, for example, Eric van Egeraat has designed Sochi Island, an artificial resort island in the Black Sea. Bahrain is developing a similar type of offshore resort. Abu Dhabi is making good use of its previously undeveloped islands, for instance Saadiyat Island, which will soon house a very different collection of wonders to Dubai in the form of new museums and galleries designed by Frank Gehry, Zaha Hadid, Norman Foster, Jean Nouvel and Tadao Ando. Even Boris Johnson's recent proposals for a new airport in the Thames estuary had a touch of Dubai about them.

Foreign architects have had a ball in Dubai, at least until recently. It's been the place where you can get away with anything. No matter how outlandish or oversized the idea, no one seemed to be saying no, and somebody else was always paying. As a result, the emirate has been waging some sort of architectural arms race with itself, each new development trying to outdo the last, while the rest of the world looked on with a mixture of disdain and envy.

The Dubai dream was ultimately unsustainable on many levels, environmental as well as financial, and it's safe to assume that most of the crazy ideas proposed for the city will never happen now, given Dubai's dire credit situation. So here are some of the craziest highlights from a future that will probably never arrive – but, you never know, still just might.

Nakheel Harbour and Tower

Legal high ...

Bad timing for SOM's Burj Dubai, which is due to open on 4 January 2010, just when a conspicuous symbol of Dubai's hubris was needed. But in the Dubai spirit of one-upmanship, plans were afoot to build an even taller skyscraper with an even shorter name: Al Burj. Originally designed by IM Pei Partnership, the tower was taken over by Australian architects Woods Bagot. It was renamed Nakheel Harbour and Tower after its backers, the state-owned property group Nakheel, which is at the heart of Dubai's current woes. The sentiment behind this stupendous tower seemed to be: "I see your 800-metre-high Burj Dubai, and raise it to over 1km. How d'you like that?"

Trump International Hotel and Tower

1980s pound-shop vase?

Surely a frontrunner in any competition for the ugliest skyscraper the world has ever seen, this 60-odd-storey atrocity, designed by Atkins, was supposed to be the centrepiece of the famous Palm Jumeirah and super-luxurious addition to the Trump brand. It looks like it was inspired by one of those 1980s vases you find in a pound shop. Mercifully, construction has been on hold for a year or so.

Dubai Towers

In the same way the peacock's tail evolved into a flamboyantly useless appendage, Dubai skyscrapers have had to resort to ludicrous contortions to stand out. From the "ignore them, they're just trying to get attention" school of design comes a quartet of bendy skyscrapers supposedly inspired by the movement of candlelight – or perhaps Jedward's hair.

Hydropolis Underwater Hotel

Plumbing the depths

Why reach for the sky when you can plumb the depths? This German-designed scheme would offer 220 bubble-shaped transparent suites, 66 metres below the surface, so guests can enjoy a privileged view of Dubai's spectacular coastal dredging operations.

The Dynamic Tower

Room with a 360-degree view

A nice idea: each of this tower's 70 floors revolves independently around its central core, so everyone lives in a revolving apartment and gets a 360-degree view of Dubai's cranescape. And from the outside, the building changes shape all the time. And it's all powered by green energy from wind turbines and solar panels. All perfectly possible, architect David Fisher assures a sceptical world.

The Dubai Opera House

Not even Dubai had the stomach for French superstar Jean Nouvel's idiosyncratic formal experiment – a strange cross between an oil rig, a greenhouse and a psychedelic light show. Nouvel's pretentious accompanying text didn't help: "It is a little like the clouds. Each person can see what attracts them, what makes them question. The architect plays only the role of provocateur, claiming innocence." Nouvel is at least building the new Louvre, in neighbouring Abu Dhabi, which promises to be stunning.

The Cloud

City on stilts

A poetic but preposterous scheme imagining a resort landscape of lakes, palaces and floating gardens, raised 300 metres in the air on slanting columns. The brainchild of Lebanese architect Nadim Karam, it's been described as "a bridge suspended between dreams and reality". Why not put a gigantic pie on stilts instead?

Waterfront City

A whole city for 1.5 million inhabitants on an artificial island twice the size of Hong Kong. Rem Koolhaas's OMA were behind the plan. Reckoning that nobody in the Gulf watched Star Wars, he put a replica of the Death Star as its centrepiece – or was that his idea of architectural satire?

Dubailand

Carnival splendour

A vast landscape of leisure, twice the size of Florida's Disney World, proposed for the interior of the emirate. Highlights include four theme parks, five golf courses, life-size replicas of some of the world's landmarks, a zillion hotels, a Beauty Museum, and, of course, another "world's largest shopping mall".