What makes a Classic Lamp?
Or maybe I should say "Who makes a classic lamp" because thats the easy answer. Without a doubt, Flos must have contributed more classic designs that any other manufacturer:
https://flos.com/en/gb/I'm sure everyone will recognise the famous Arco which has just celebrated its 60th anniversary, designed by the legendary Achille & Pier Giacomo Castiglioni. It really has stood the test of time, and its latest incarnation, the limited edition with a crystal base, is superb.

The Globall is also one of their renowned classics. Cheaper copies have been made but none of them come close to the quality of light and unique aspherical shape. The surface of the lamp has a fine but smooth acid-etched finish which combines with the thickness of the glass to produce a beautifully soft, almost shadowless light:
But Flos isnt the only company still making classic light fittings:
Le Corbusier
Most of Le Corbusier's lamps were bespoke designs for specific architectural projects of his in the early part of the 20th century but their influence can be see in the many copies and adaptations in homes and hotels throughout the world. His influence was so great that there are currently several specialist manufacturers and retailers where lamps to his original design can still be purchased.

The Escargot lamp above (dog not included) demonstrates the designer's understanding of how light shouldn't always come from above and in fact benefits from emanating in various directions to create the right mood. Whilst this particular design isn't seen much today, it continues to inspire the production of of low level wall washers, uplighters & soft-source floor lamps.
On the other hand, examples of the Marseille wall lamp can still be seen in many restaurants and hotels in its original form and has also inspired a multitude of variations. In the same way, many homes still have wall lights similar to the ones below which have been copied and adapted extensively for over a hundred years.
Davey Lighting
For a more industrial look, Davey Lighting (makers of the original miner's lamp), continue to produce their range of ship's fittings to the same design and these solid brass & copper fittings have gained renewed popularity in many gardens and restaurant terraces due to their water resistant construction. The mast light below is particularly useful for lighting steps and pathways whilst the large industrial pendant has gained popularity in domestic kitchens.
Worth a mention
The Italian manufacturer, Linea Light is certainly one to watch and I'm sure many of their lights will become classics over time. I particularly like their latest collection of garden lights, Rolling Sky.
Whilst most of the best light fittings still seem to originate in Italy & other parts of Europe more British manufacturers are starting to emerge so its worth taking the time to track them down and maybe consult a lighting designer to put you on the right track.