Cardiff (Wales) has many diverse sections each with their own naming conventions.
The main thouroughfares got their names early, and usually relate to their main destination, so the main road out of Cardiff to the East is Newport Road, to the West is Cowbridge Road, to the North (from Cowbridge Road) is Llandaff Road, to the South is a bit wet as Cardiff's a port!
In Canton, beyond Llandaff Road, the side roads to the South take their names from English counties, to the North, from Welsh counties.
In Splott (yes, there really is such a place) you get:
Metals, Metal St. Gold St. Silver St. Tin Street. etc
Precious stones, Pearl St, Ruby St, Topaz St, Sapphire St.
In Riverside (From Cardiff General station to the marshalling yards in Canton) you have famous engineers:
Trevithick St, Stephenson St. Wells St Brunel St etc.
Off Cathedral Road (a newer main thoroughfare leading from the city centre to ... the Cathedral) the streets on the side nearest the river take their names from Welsh saints, Teilo, Dogo, Berthwyn, Dyfrig,
Even a new estate from the end of the 20th century (Danescourt) takes its street names from the past Bishops of Llandaff