GS - Spheroidal graphite cast iron - a special cast iron in which the crystallization of carbon has been slowed down, which makes it close to steel - also called ductile iron (Thanks to Vuori Susi for the clarification)
It is not clear whether it is listed as URBAINE_S or URBAINE_5, it is clearly something "urban". If you know the details, click on the question mark
The lid is similar to another manhole cover made by the same manufacturer