The highest point of a mountain or structure; summit or peak. Can also mean the pinnacle of something figuratively.
朝早く出発して山の頂上に着いた。
We left early in the morning and reached the mountain summit.
プロジェクトはついに頂上に達した。
The project finally reached its peak.
頂上からの景色は素晴らしかった。
The view from the summit was wonderful.