The A5205 is a short link road on the northern edge of central London. It was originally numbered B508 but presumably gained its current number in the mid-1920s as it fits into the original numbering scheme, that four-digit A-roads in central London would be of the form Ax2xx.
The road starts at traffic lights on the A5 Maida Vale and heads east along St John's Wood Road. This is a primary red route in order to divert traffic from the A5 to the A41 at this point, although in reality much of the traffic probably chose to do that earlier. We cross the B507 at traffic lights and then go past Lord's Cricket Ground to reach the A41 at traffic lights. There's a short multiplex to the right to a roundabout and we continue along the non-primary Prince Albert Road.
The road follows a gently curving route skirting the edge of Regents Park. As such there are residential buildings to the left and open space, with the occasional building, to the right. For a short section we run along the boundary between the London Boroughs of Westminster and Camden, where there is open space to the left, Primrose Hill, whilst London Zoo is on the right although it's not accessible from this road. We cross the Regents Canal and pass the zoo car park (which isn't accessible from this road either) before we end at traffic lights on the A4201.