STOCKHOLM -- I seemed to be flowing amid a river of wildflowers.

I was at Skansen, Stockholm’s open-air folk museum and zoo, and all around me, bobbing heads — many crowned with wreaths of freshly plucked blooms — made their way down the cobblestone streets. We were on our way to a grassy area to celebrate Midsummer, when Swedes sing and dance around the maypole, deck themselves with flowers and revel in the beauty of summer.

Near the grounds where the maypole would rise, the literal centerpiece of the party held at the end of June each year, I spied a white-haired man climbing a hill, a light blue and yellow Swedish flag tucked under one arm and a wicker picnic basket dangling from the other. A woman wearing a bright red vest, a long dark skirt and a starched white scarf covering her hair, walked beside him. Around them, a multitude of festivalgoers were immersed in their own forms of fun.

Nearly every piece of the green ground had been trampled by people who were gathering flowers, picnicking or simply basking in the pure summer sunshine at Skansen, a 75-acre spot with 150 historic homes, shops and churches representing cultures from around Sweden (www.skansen.se; click on “English” at upper right).

Many revelers — young and old, girls and boys — foraged for flowers, long grassy stems and birch limbs from which to weave their Midsummer’s crown. None were immune to the charm of this, the biggest of Sweden’s summer gatherings.

I’d come to Sweden to experience the ancient ritual and great communal festival of Midsummer, a celebration of the summer solstice, longest day of the year. While the solstice is celebrated in many places, Swedes — who have endured a dark winter — relish summer, when the sun sets near midnight, with particular gusto. It seemed all of Stockholm was gathering around the maypole, many dining on the classic picnic of the day: new potatoes, pickled herring, sour cream and chives, hard-boiled eggs topped with caviar, and strawberries.

Before feasting began, though, the long heavy log of a maypole was decorated. Young girls dressed in colorful folk costumes, many sporting braids, strolled up to the horizontal pole to attach greenery, wreaths and daisies. Then eight or nine Swedish men stepped in, looking the part in billowing white shirts, vests and knickers. They gathered at the top end of the heavy, roughly 40-foot-long maypole. There, they planted smaller poles beneath the maypole to brace it as it climbed ever higher into the sky. After 10 minutes of careful, heavy work, the maypole stood upright, shimmering green in the sun.

The men bowed. Clapping followed, along with fiddle music and dancing. First, costumed folk dancers encircled the maypole. A song or two later, the ground swelled with the entire crowd, hands locked together, snaking around the maypole. I was somewhere in the layers of concentric circles, smiling along with my fellow dancers amid swells of laughter.

Everyone but one in my eyesight was smiling. A serious looking boy in a Hollister shirt was sandwiched among a group of giggling teenage girls, their hair festooned in freshly plucked wildflowers. Nearby, a young girl with 10 numerals scrawled in ink onto her arm held hands with another young dancer. The numerals were a parent’s phone number, marked on her arm in case she got swept up in the moment and swept away in the crowd. It can happen when a sea of thousands dance to the rollicking “frog dance” song (sma grodorna).