The Three Rivers Arts Festival commemorated its 50th anniversary with a reception and retrospective hosted by the Pittsburgh Cultural Trust last Tuesday. A space at 907 Penn Ave. was crowded with history: the artists, founders and leaders who have contributed so much to the fabric of the festival. Cultural Trust president Kevin McMahon welcomed guests, including many of the women who started the festival as part of the Carnegie Museum of Art Women's Committee Junior Council. Also there was Marguerite Jarrett Marks, who was brought in to organize the new, revised festival, and board chair Deb Acklin.