Thomas Sieverts (born 8 June 1934[1]) is a German architect and urban planner.
Sieverts calls this the Zwischenstadt, or "in-between city", as it exists between old historical city centres and open countrysides, between place as a living space and the non-places of movement, between small local economic cycles and the dependency on the world market.
In 2008 a group calling itself "suddenly" commissioned the American writer Diana George to make a new translation of Zwischenstadt which they published as Where We Live Now (the English phrase George chose as the translation of Sieverts's neologism "Zwischenstadt").
In October 2008, Sieverts came to Portland, Oregon, on the occasion of the book's publication to take part in a week-long symposium about his work, also called suddenly.
He served as Scientific Director for the International Building Exhibition (IBA), Emscher Park, Gelsenkirchen from 1989 to 1994, and Fellow at the Institute of Advanced Studies, Berlin from 1995 to 1996.