WORCESTER — The Mechanics Hall Concerts Plus series continues with two free recitals presented on Facebook and YouTube Feb. 24 and Feb. 28 in honor of Black History Month. Acclaimed organist Nicole Keller will perform works by Renaissance/Baroque composer Jan Pieterszoon Sweelinck and 20th-century Black American composer Florence B. Price at 7:30 p.m. Feb. 24. Keller, who is based in Cleveland, recently visited Worcester for the first time performing a livestream concert at Trinity Lutheran Church and recording the recital in Mechanics Hall. She has given concerts at venues ranging from as St. Patrick’s Cathedral in New York City and Cathédrale Notre Dame in Paris to The Kazakh National University for the Arts in Astana, Kazakhstan. She is on faculty at the Baldwin Wallace University Conservatory of Music and is the associate organist at Trinity Cathedral, Cleveland, and helps run its BrownBag program.