When it comes to bank holidays or national celebrations there is no day that is as important to the Swedes as Midsommar. Even christmas is not as big here.
Swedish Midsommar is celebrating traditionally the longest night in the year (in northern parts of Sweden the sun does not set at all). Midsummer Eve, which is the festive day is always a Friday between the 19th and 25th of June. Therfore it can be some time, that the actual date is not the meteorological summer solstice. 

Anyway Swedes plan this day very much in advance. Usually Stockholm City is empty by Thursday afternoon, since all people leave for the countryside to celebrate in their "Stuga" (countryhouse) by the water.

The celebrations start already in the early morning, where especially kids and girls or women put a lot of work and effort into making a traditional "krans" or flower crown. Even man are doing this as well, but more with green leaves and less flowers. 

Their actual task is to built and lift the maypole, which is used as central spot for dancing in the afternoon. Watched and cheered by the others, it takes them quite a while to lift that thing and secure it on the ground. When the pole finally stands, everyone applauds and the swedish "dansband" similiar to German Schlager starts to sing their songs. Meanwhile everyone has drunk already more than 5 glasses of beer, so the Swedes can finally let go and start the very famous frog dance to increase fertility. (i recommend you to watch some videos on youtube)

This is one of the opportunities in the year, where you can actually make contact to strangers and do not need to feel ashamed, since they will not remember you the next day anyway.
After dancing around the pole, you might have hooked up with someone or celebrate more privately at your place with a barbecue and svensk färskpotatis. If you were unlucky and did not pick someone up, you still got the chance to pick 7 types of flowers, while crossing 7 fences and put them under your pillow. If you believe very hard in it, you might dream of the man you will marry.

But how to look on this very special day in the year? Every female wears a white dress, no matter how cold it is (maybe around 15°c) and a huge flower crown. But of course you get extra attention if you have a very nice crown, so better put a bit of effort into it. 

You can buy the kit (a big wire hairband, satin ribbon and a roll of wire to attach flowers) in almost every flower shop around town the days before. Traditionally you should gather 7 types of flowers, but at that time not many nice flowers grow around. So you have to invest some money to buy them. It is basically really easy since you attach your flowers with the wire around the hairband, but it can be a bit tricky if you do it for the first time. If you have your flower crown and a white dress (maybe rubber boots and a rain cape as well) you are ready to go. 

Do not forget to get your supply of beverages at systembolaget a few days before, since everything shuts down Friday afternoon.

There are a few places around town, where you can go as a non-swedish person without swedish friends who own a country house.There is always a big celebration at Skansen (sometimes the royal family attends as well). Otherwise there is a Maypole rise in Bromma. If you like to escape the city, one of the nicest traditional Midsommars can be celebrated on an Island in the archipelago called Grinda. If you plan early you can even rent one of the popular small houses and stay on the island for the whole weekend. Ferries leave regulary from Stockholm and it takes around 3h to get there.