|Location Map ( geo)|
|Distance:||5.5 miles (8.9 km)|
|Met:||B4422, A5, B5112|
|Now part of:||A4080, B5112|
|Route outline (key)|
The B4423 was, aside from a last minute allocation in Carmarthen, the highest numbered 4-zone road in the 1922 Road Lists. As might therefore be expected, it ran to the west of Anglesey near the end of the A5.
The road had a roughly north-south route, starting at the western end of the B4422 in Llanfaelog and heading vaguely northwards. It crossed the A5 near Bryngwran before ending in Trefor, from where the B5112 headed west to Bodedern or north to Llanerchymedd.