Irena,
I have the same question as Fred. I have German and Italian passports, so, it would be wonderful if you could answer the question for those nationalities as well as Fred’s.
EU citizens can apply for a tourist visa that allows a single, double or multiple entry into Russia for tourism, participating in exhibitions and auctions or medical consultations (not treatment). It is also allowed to hold short-term business negotiations. Visa validity period is for up to 90 days for single and double visas and up to 6 months for a multiple visa. At the same time stay period in the Russian Federation is limited to 30 days for single and double visas and for 90 days in every 180 days term for multiple tourist visas.
You need a tourist invitation according to your planned stay. You can get it at this link: https://russiable.com/visa-support/