Seats without membership: the two non-member States that hold Permanent Observer missions at the UN

Background

This background goes with news from the Vatican, whose Holy See sits at the United Nations without being a member of it.
The United Nations lists two non-member States that have a standing invitation to take part as Observers in the sessions and the work of the General Assembly.
They are the Holy See and the State of Palestine.
Each of them maintains a Permanent Observer Mission at United Nations Headquarters.
The Permanent Observer Mission of the Holy See to the United Nations represents the Holy See there.
Palestine was accorded non-Member Observer State status by General Assembly resolution A/RES/67/19 of 29 November 2012.
Addresses and contact details of these missions are kept in the United Nations Blue Book.
An Observer may take part in the work of the Assembly but is not a Member State of the United Nations.