The A4218 is a short A-road in the Pembrokeshire town of Tenby.
The road starts on the A478 Narberth Road on the northern side of town. That road TOTSOs here, presumably catering to through traffic. The road heads south along Serpentine Road, crossing the railway line before bearing left onto Broadwell Hayes. It descends to meet the B4318 Heywood Lane before continuing on to the railway viaduct ahead. There is a double mini-roundabout beside the viaduct where the A4218 ends on the A4139. Through traffic continues ahead whilst the town centre is to the left on the far side of the railway line (although we could have just remained on the A478).