Our house is close to the centre of Oslo. You can walk to various parts of the city, take the bus or the tube. Or you can borrow our Bicycles. You can study what to do on this official site of the city: https://www.visitoslo.com/
Frognerparken is a must: https://www.visitnorway.no/reisemal/ostlandet/oslo/listings-oslo/frognerparken/16403/
Travel to the islands in the fjord: https://www.visitnorway.no/reisemal/ostlandet/oslo/listings-oslo/%C3%98yhopping-i-oslofjorden/15222/
Walk and enjoy Grunerløkka: https://www.visitoslo.com/en/activities-and-attractions/boroughs/grunerlokka/
Enjoy the food, location and atmosphere of Vippa: http://www.vippa.no/photos/
Walk on the roof of the Opera: https://www.google.com/maps/uv?hl=no&pb=!1s0x46416e8ba321f715:0x1cb6a7c6a2a2d611!2m22!2m2!1i80!2i80!3m1!2i20!16m16!1b1!2m2!1m1!1e1!2m2!1m1!1e3!2m2!1m1!1e5!2m2!1m1!1e4!2m2!1m1!1e6!3m1!7e115!4shttps://lh5.googleusercontent.com/p/AF1QipM0oqLgxsES1T-um0A0sGjOgJ2vjxVSKO6ADGnQ%3Dw373-h250-k-no!5soperataket+-+Google-s%C3%B8k&imagekey=!1e10!2sAF1QipM0oqLgxsES1T-um0A0sGjOgJ2vjxVSKO6ADGnQ&sa=X&ved=2ahUKEwiXm6vj-LDgAhWd7aYKHWjYDBgQoiowDnoECAYQBg
Go hiking or cycling in the nature: https://no.tripadvisor.com/Attraction_Review-g190479-d656596-Reviews-Oslomarka-Oslo_Eastern_Norway.html
Have nice meals in some of the many restaurants: https://www.visitoslo.com/en/restaurants-nightlife/restaurants/
Walk and stop on nice sites along Akerselva: https://www.visitoslo.com/en/articles/akerselva-river/
Visit the surroundings by train. I will recommend a tour to Bergen and Flåm - which is a detour on the trail to Bergen. https://www.visitnorway.com/plan-your-trip/getting-around/by-train/