Welcome to the wonderful world of superstructures. The debate on modern architecture remains as subjective as ever as the Barbican Gallery (a prime example of London's eclectic architectural mix) kicks off London's Architecture Week with a look at some of the most outstanding designs over the past 50 years.

From the far-fetched pop architecture projects of Archigram - a 1960s vanguard in experimental design, of which only three architectural projects were actually realized, none of them buildings - and artist-turned-architect Constant Nieuwenhuys, to the fantasy structures of the UK's Future Systems and Dutch wunderkind Rem Koolhaas, these 20th and 21st century feats of engineering bedizen and bedazzle against historical horizons. A peek into the future or flights of fancy?