Save for the parade of stupendous hats, there was little to alert passersby to the royal wedding Saturday morning in downtown Washington: No horse-drawn carriages. No visible security. Hardly more photographers than at your normal wedding.

But a royal wedding it was, as a D.C. public-relations woman became an Austrian archduchess.

Kathleen "Katie" Walker and her groom, Archduke Imre of Austria, depart Saint Mary Mother of God Church in Washington, D.C., on Saturday. (Marlene A. Eilers Koenig)

The bride: Katie Walker, 26, a Cincinnati native who until recently was communications director for Catholic Charities of the Diocese of Arlington.

The groom: Archduke Imre of Austria, also 26, great-grandson of Charles, the last ruler of the Austro-Hungarian empire.

Right now you’re thinking, “Wow. How’d she find an archduke?” Well, by going to church. Ken Wolfe, a friend of the bride who sang in the Gregorian chant group at her wedding, tells us the couple met two years ago at Chinatown’s St. Mary Mother of God, at a Mass in honor of the emperor, beatified by Pope John Paul II for his attempts to end World War I. Imre returned to Washington for an internship last summer at the conservative-libertarian Atlas Network. In December, they announced their engagement.

About 350 guests witnessed the wedding Saturday back at the parish where they met, a traditional Latin Mass with Bishop Paul Loverde of Arlington in attendance.

Walker seems to fit the mold of the modern princess-by-marriage: a career of her own, a natural with advocacy (she has been active in antiabortion circles) and fantastic hair. The groom may not have a throne to aspire to, but he does have an impressive pedigree — cousins from the Luxembourg and Liechtenstein monarchies were among the guests captured in photos by Marlene Eilers Koenig , a research librarian and European royalty expert who staked out the wedding from the sidewalk. Koenig tells us that the bridal party departed the church in a stretch Hummer for the St. Regis reception.

Walker recently left her job to prepare for her new life in Europe, we’re told. The couple, off on a super-secret honeymoon, did not reply to our e-mails.

See more photos of the Austrian royal wedding -- including some impressive hats — at Koenig’s Royal Musings web site here and here.

Also in The Reliable Source:

Quoted: Nicki Minaj explains her Romney lyrics

Hey, isn’t that . . . .?: A lot of Redskins clubbing

No, a lady biker did not sit in Joe Biden’s lap

Love, etc.: Blake Lively and Ryan Reynolds wed

Tim Geithner had a pretty good finish in Nation’s Triathlon

Making the stars align: Impact Arts + Film throws parties to bridge the D.C.-L.A. divide