Ooh-hoo-hoo...I've got reams of stuff on Seilen... where to start...?
Seilen is called by some the City of Dreams. However, most call it the City of Thieves. It lies on the river Murkenmire, and is a honeycomb of walkways, bridges, and canals. The second oldest of the Seven Cities, it was founded by refugees from Talossa, under the leadership of the city's great hero Seilos. As Talossa suffered under the maddened rule of the Illius family, Seilen became the pre-eminent harbor on the Aguire, a postition it has more or less kept for centuries. Seilen is ruled (and has been so more or less since its founding) by the Five Families, a group of powerful aristocrats who wield an incredible amount of control over the city. The one of the Families holds the office of Primus, the lord of the city. They are elected by the Advisory Council, a mostly symbolic concession to the populace on the part of the Five Families. Presently the Quirinius family is in control, under the rule of the Regent Alyssa Quirinius, as the present Primus, her son Timon, is only two years old.
Arguably more powerful than the Five Families is the Merchants' Emporium, a sizable alliance of guilds that more or less control trade on Eldheim and Sleurith. Treacherous and scheming, the Emporium is often torn by intrigue and politics, but is too potent a force to be ignored.
And finally there are the thieves. Most (but not all) thieves in Seilen are members of two rival "guilds"--Thieves' House, and the Grey Rats. Thieves' House is known for its secretiveness, and skill, the Grey Rats for their numbers and persistance. Both groups are bitter rivals.
Seilen is a treacherous place, known for backstabbing and double-dealing. Apropriately enough, it has two patron dieties--Surya, who all stress their alliegence to, and Thanatos, who all cate favor with. The present head of the church of Thanatos, Astur Vermis, is one of the most charming, powerful, respected men in Seilen. Naturally, most people are terrified of him.
And finally, Seilen is home to Aert of the Silver Robes, the mysterious (and quite possibly insane) wizard of mysterious origin, who built his tower there a couple centuries ago, and has since refused to leave. He generally doesn't come out often, but has been known to leave to stop criminals and adventurers of an especially vile nature...