Take advantage of free-admission hours at the City's only hands-on science and technology center, originally built as a pavilion for the 1964 World's Fair. The New York Hall of Science, also known as NYSCI, houses more than 450 kid-friendly exhibitions permanently on view—such as Search for Life Beyond Earth—plus special shows on tour, currently including Molecules & Health: The Shape of Science, which explores molecules and how they affect the makeup of our bodies. Admission on March 4 is free from 10 to 11am. For more information, visit nysci.org.