expression, noun
first and foremost; top priority
Idiomatic expression literally meaning 'plot 1, block 1', used to emphasize that something is the most important thing to address first, like the starting point of a plan or policy.
教育改革は、この政権の一丁目一番地だ。
Education reform is the top priority of this administration.
まずは顧客満足が一丁目一番地です。
First and foremost, customer satisfaction is the most important thing.
From the address notation '1-chōme 1-banchi', the very first plot in a town, metaphorically extended to mean the starting point or highest priority.