Since there are no buses today either you might like to go on a trip with the subway.
Luckily there are free art exhibitions and tours very often. All you need is the subway ticket which you probably already have.
Tuesdays, Thursdays and Saturdays at 13.30 in Swedish and at 15 o’clock in English there are tours that tell you about all the great and fun art in the Stockholm subway.
Be at the Central Station, SL Center Sergel Square, ticket hall towards Sergelstorg in good time. The guide chooses which stations, to visit, usually in the inner city.