Tour co-sponsored by Baltimore Heritage. Price $10. Please reserve in advance. Mount Vernon began as the estate of Revolutionary War hero John Eager Howard and grew to be the place to live for Baltimore’s rich and famous in the mid-19th century. The Garrett family, owners of the B&O Railroad, the Walters, founders of the Walters Art Museum, and other families, built and lived in handsome mansions along the four parks of Mount Vernon Place surrounding the Washington Monument. The recent…