The FTZ - the “Fernmeldetechnisches Zentralamt der Bundespost” (central telecommunications office of the Federal Post Office) was located in Darmstadt from 1949. Until the end of the 1980s, its purpose was the development and control of new communications equipment and systems. In 1989 the FTZ became part of the newly formed Telekom. Part of the FTZ, the technology centre, worked on topics such as multimedia and fibreglass communications. From 2002 to 2005, on the site of the former FTZ, "Telekom-City" was built with several Telekom facilities, among them the internet subsidiary T-Online.

By 2014, the Technology Centre (TZ) Rhein Main had become an open, modern fifty acre office park with 25 highly modern building projects. With many green areas and a comprehensive service offer for tenants, ranging from a medical centre and kindergartens to recreation areas, it promises to support a healthy work-life balance.