Nearly three-dozen queens of past Iowa State Fairs will return to the State Fairgrounds this weekend as part of the festivities surrounding the Fair’s sesquicentennial year. Kathie Swift, the Fair’s PR director, says the format for the State Fair Queen contest has been the same since 1964, and 33 of the queens who’ve been crowned since then are returning this weekend and will be on hand when the 2004 Iowa State Fair queen is selected. There’s also going to a reunion of former champions of the Bill Riley Talent Search, gathering on the final Sunday of the fair just before this year’s talent show. The Fair opened yesterday with dedication of a new monument to commemorate this 150th year. Outside the northwest corner of the Agriculture Building there’s a permanent memorial to the sesquicentennial in the shape of a six-ton granite ball. A map of the world is engraved on the granite, and the ball floats in a fountain that has just a few inches of water. There are also markers on the grounds engraved with quotations from the early days of the fair.