head temple of a Buddhist sect
Specifically the main temple that oversees a Buddhist sect. Used in religious contexts.
Chion-in in Kyoto is the head temple of the Jodo sect.
headquarters; nerve center
Figurative extension: the central base or command center of an organization, often used in business or political contexts.
あのビルが我が社の総本山だ。
That building is our company's headquarters.
警察の総本山である警視庁に問い合わせた。
I contacted the Metropolitan Police Department, the nerve center of the police.
Shingon Buddhism, which has Mt. Koya as its head temple.
Silicon Valley is the nerve center of the IT industry.