Italian to English Marketing Construction / Civil Engineering

Hi there,

I am translating an advert selling a villa in Tuscany. It describes the house as being on two levels connected by a beautiful Tuscan staircase and then:

oltre ad una parte di servizio parzialmente seminterrata

I am unsure if this is referring to a bathroom, or something like a utility room.

If anyone has any tips I would be grateful.

Grazie!