After having being separated for hundreds of years, two iconic, Renaissance paintings by artist Sandro Botticelli have been reunited, first in Italy and now in Boston at the Isabella Stewart Gardner Museum. They are "The Tragedy of Lucretia,” purchased in 1894 by Isabella Stewart Gardner and first Botticelli to land on US soil, and “The Story of Virginia,” from the Accademia Carrara in Bergamo. They are the core of a new exhibit in the Gardner Museum's Hostetter Gallery (in the new wing), "Botticelli: Heroines + Heroes," through May 19.