adverb
Formal or literary adverb marking a transition or conclusion, similar to 'hereby' or 'at this point'. Often used in speeches, announcements, or formal writing.
ここに、本日の会議を終了いたします。
Hereby, I declare today's meeting closed.
ここに、新たな時代の幕開けを宣言する。
Here, we declare the dawn of a new era.
ここで is the locative 'here' (at this place), while ここに is a formal transition marker meaning 'now' or 'at this juncture'.
Compound of ここ (here) and the particle に, but the meaning has shifted to a formal discourse marker rather than a literal locative.