These ships, initially rated as second class cruisers, were built to a series of designs, known as the "Bristol" (five ships), "Weymouth" (four ships), "Chatham" (three RN ships, plus three RAN ships), "Birmingham" (three ships, plus one similar RAN ship) and "Birkenhead" (two ships) classes – all having the names of British towns except for the RAN ships, which were named after Australian cities.