CINCINNATI— The opening of the 624-room Hilton Cincinnati Netherland Plaza has been announced by Hilton Hotels Corp. Formerly the Omni Netherland Plaza Hotel, the Hilton Cincinnati Netherland Plaza will continue to be operated and managed by Belvedere Hotels Ltd., under a franchise license agreement with Hilton Hotels Corp. Recognized as a National Historic Landmark in 1994 and a charter member of the National Register of Historic Hotels, the Hilton Cincinnati Netherland Plaza features elaborate wall and ceiling murals and frescoes, intricately detailed staircases and 1930s French Art Deco architecture. The 29-story hotel will celebrate its 75th anniversary in 2006.