A Mondia was a classic Reynolds 531 frame.
There were at least 3 models, and I have seen reference to a couple of others. There is a wikipedia entry for Mondias that describes some of the models and details of the two most common: the Super and the Special. The third called "Prestige" was described in a January 1977 "Bicycling" magazine article which can be googled. It may have only been made for a year or two, and designed for criterium racing.
I have a Mondia Super made in 1978. It has Prugnat lugs, and I built it with my own selection of Campy, Shimano, and Cinelli components. It is my favorite bike and I was lucky to find this frame when I did.
The best and most special feature, a side from the Renolds 531 frame, is the fade paint on chrome. Although many later brands began to offer fade paint jobs, Mondia was one of a number of Swiss manufacturers to mass market this paint scheme and, arguably, few other bikes of the era compare in attractiveness.
Here are pictures. The serial number is 291078.
The distinctive fade chrome not seen after about 1980.
Prugnat lugs replaced Nervex in the late '70's.
I would imagine that yours does date from around 1972-73.
If you have the financial means I hope that you will decide to have it repainted
exactly as new. There are decals for Mondia available on e-bay.
You will be hard pressed to acquire another bike from this era that is as unique, and also somewhat less common. And it will last you a lifetime.