Haggai, along with Zechariah, are the two prophets commissioned by God to exhort the people to rebuild the temple after their return from exile. Haggai, Zechariah, and Malachi are the only three post-exilic prophets.
Mentioned in this book are Zerubbabel, the governor over the people in Judah, and Joshua, the high priest (of no relation to the Joshua who guided Israel after the death of Moses).
The location for Haggai's prophecy is Jerusalem. The words of this book were delivered in Jerusalem to Jerusalem.