This is the road from London to Brighton, which has been closely linked with motoring and the enjoyment of the open road since the early twentieth century. For over a hundred years people have been tearing through the South Downs to the coast for the sheer thrill of hitting the road, and even today the annual classic car rally down to Brighton is just one of many events that trace the A23's route to the seaside.
The modern route really begins at the M25, with the A23 into London from there being not much fun at all. The M23 is the first part of the route, connecting to Gatwick Airport and bypassing Crawley before passing the baton back to the A23, which completes the run from there to the A27 at Brighton as a high-quality dual carriageway. The A23 is arguably the more enjoyable bit of the drive, with more interesting hills and corners and the iconic stone pillars framing the long straight road on the final approach to Brighton.
The M23 is an important road in its own right but it's only a part of what it was meant to be, as evidenced by its first junction being numbered 7. It was supposed to continue further north, through South London, to reach the proposed motorway replacing the South Circular, Ringway 2. The horrific line it would have taken, ploughing through affluent suburbs and irreplaceable parkland, made sure the plan was well and truly buried. Unfortunately, this means there is no single obvious route to continue into London from the end of the M23, and the A23 itself is not much more than a local road past Croydon.
You're not looking at the whole M23 and A23
This page only deals with the parts of the M23 and A23 that are classed as motorway or that have motorway characteristics. Any other sections of this road won't be featured here and will not count towards the mileage shown below.