Once in Västerås, almost every attraction is well within walking distance or can be reached in no time by public transportation. The city is not very touristy, which could be considered a good thing. This is one of the larger industrial cities in provincial Sweden, situated 110km to the west of the capital.
If you are spending a day in Västerås we recommend that you start at the train station, and then walk through the Vasa Park, to the Museum of Art (http://www.vasteraskonstm...). Then continue to the Turbine House, which is one of Sweden's first power plants, constructed in 1890 by ASEA. From here you can view the castle (http://www.vastmanlandsla...), famous for the Parliamentary decision of 1527 when King Gustav Wasa abolished Catholicism in Sweden, making Sweden a protestant country. The Västerås castle was originally erected around 1200, but what is seen of the castle today was built by Gustav Vasa mid 1500. The castle is a rather ugly building clearly meant for defence and not to impress by look. Nowadays it is a museum.
Later on you may want to follow Svartån creek northwards to the older parts of Västerås Stora Torget and the surrounding streets are especially nice, where you also find the old Cathedral dating back to the 13th century. The cathedral is definitely worth a visit. The oldest parts of the cathedral was built around 1200. The oldest son of Gustav Vasa, Erik XIV, is buried in the church. Erik XIV is mostly famous because he was killed by poisoned pea soup. Summertime appointments for guided tours can be made between 11 am and 1 pm at the tourist office. A stone's throw from the Cathedral lies Church Hill Kyrkbacken, which is the only major part of central Västerås not destroyed by the building programs of the 1960s. Really nice surroundings, where you can walk on the small and winding lanes and look at some of the oldest buildings in Västerås and, if you like, visit local arts and crafts shops.
Anundshög, which lies a few kilometers east of Västerås, is a nice place for a picnic during the summer. Anundshög is an ancient burial mound, 14 metres high and 60 metres across, making it the largest in Sweden. Next to the mound there is two big stone-ships. Take bus 40 towards Tortuna or go by car.