From Roader's Digest: The SABRE Wiki
|From:||Castle Street (ST157871)|
|To:||Ton-y-Felin Road (ST158873)|
|Length:||0.1 miles (0.2 km)|
|Now part of:||B4600|
|Route outline (key)|
The A4057 was originally allocated to a short length (under 200 yards) of Bedwas Road in Caerphilly. This cut the southeast corner between the A468 (now B4600) and A469 (now B4263) outside the castle.
Surprisingly, unlike many other 4-digit A roads becoming defunct in 1935, the number has never been re-used elsewhere.