The blue and gold of the Swedish flag flapped proudly inside Palo Alto City Hall Monday night as the city enthusiastically welcomed a Swedish delegation and celebrated its quarter-century-old relationship with the city of Linkoping.

The two high-tech hubs formed their "sister city" relationship in 1987, under then-Mayor Gail Woolley. On Monday night, Woolley joined a large group of former and current elected officials to mark the 25th anniversary of the partnership and to welcome Linkoping (pronounced "Lin-cher-ping") Mayor Ann-Cathrine Hjerdt and a delegation from Sweden to Palo Alto.

Current Mayor Yiaway Yeh led off the council's regular meeting by reading a proclamation honoring the long friendship between the Scandinavian city, which has been around since the time of Viking invasions, and the California one, which has a high school that boasts Vikings as its mascot.

There are other similarities. Each city boasts a major university and a thriving high-tech sector. While Palo Alto draws much of its talent and identity from Stanford University, its Swedish sister has Linkoping University. And while Palo Alto has a large community of start-ups and major technology firms such as Hewlett-Packard, Linkoping boasts Saab AB, an aerospace company that manufactured planes for the Swedish military.

Yeh's proclamation noted the two cities decided to join forces to "foster friendship, appreciation, understanding, collaboration and citizen exchanges" and that they have "forged a bond of friendship and appreciation for 25 years through many cultural and education exchanges, the arts, music and collaboration in community affairs."

In accepting the proclamation and a ceremonial key to Palo Alto, Hjerdt thanked the City Council for its welcome and stressed the major role the two universities played in establishing the contact between the cities. She said she looks forward to continuing the relationship in the future.

"The delegation from Linkoping is very inspired -- not just to re-establish existing contacts but also make new contacts in new areas," Hjerdt said.

Yeh also proclaimed the period between Sept. 10 and Sept. 14 as "Linkoping, Sweden Week" in Palo Alto. The Swedish delegation will be ushered by its Palo Alto hosts through a series of events this week, culminating in a reception Thursday evening.

Linkoping is one of six municipalities with which Palo Alto enjoys a sister city relationship. Palo Alto formed its first such partnership in 1963, with Palo, Philippines. Its other sister cities are Oaxaca, Mexico (1964); Enschede, The Netherlands (1980); Albi, France (1994); and, most recently, Tsuchiura, Japan (2009).