Chase Center on the Riverfront, 815 Justison St., Wilmington, DE 19801. One of the  nation's most highly acclaimed antiques shows celebrates its 50th anniversary with a spectacular showcase of art, antiques, and design. Featuring the finest offerings from more than 60 distinguished dealers, the Delaware Antiques Show,      presented by Winterthur Museum, Garden and Library, highlights the best of American antiques and decorative arts. This year's honorary show chair and keynote speaker is Lady Henrietta Spencer-Churchill, an internationally recognized interior designer and author, and the eldest daughter of the 11th Duke of Marlborough. Cost is $15 for nonmembers and includes access to all three days of lectures and exhibits.   For tickets and information, show hours, special events and offers, and directions to the show, call 800.448.3883, or purchase tickets online, Winterthur.org.