The official website for Mainz is quite helpful for the prospective visitor, although its translations are sometimes funny and the content can be wordy without being informative (particularly in the section on sports).  The suggestions to be found here regarding shopping, events and festivals, sightseeing, and other such pages provide most practical trip advice for travelers to Mainz .

The online information linked to above should suffice, even for the first-time visitor, but should you wish to communicate with someone more directly, try using any of the following contact data for further visitor recommendations:

Touristik Centrale Mainz
Brueckenturm am Rathaus
D-55116 Mainz
Telephone: 49-(0)-6131-28621-0
tourist@info-mainz.de

The official tourist presence for Mainz online is a lot prettier, but not as comprehensive: this site is better for booking and brochures. 

Located in the province of Rhineland-Palatine, the tourist office for this greater region has an excellent array of pages pertaining to its various cities, although an unofficial link also dedicated to drawing visitors into the R-P contains an even better menu of links from which to plan day trips to cities such as Trier, Germany’s oldest, or Worms. 

You can also contact this regional Tourist Board at:

Rheinland-Pfalz Tourismus GmbH
Löhrstraße 103-105
56068 Koblenz
Germany
Telephone: 49-(0)-261-915-20-0

Finally, click here for Germany visitor info, email info@d-z-t.com, or visit

German National Tourist Board
Beethovenstraße 69
60325 Frankfurt/Main