Almost all major office buildings have names. The word for "building" in Japanese is "birudingu," originally coming from English. As it is quite a long set of sounds for Japanese, in modern use it has become just "biru." (pronounced "be-ru" (NOTE: This is not to be confused with another foreign loan word, "beer" which is pronounced "beee-roo", with a lengthened "e" sound.)

A building is almost always written in postal addresses, however, it is on a separate line such as:

Mori Building 3F
2-3-4 Akasaka

It is never included as part of the numeric address such as (incorrectly) :

2-3-4 Akasaka Mori Building 3F