You could stay almost a whole day in that area. The Washington Monument is located right there and you can climb to the top lookout level. The Walters Art Museum (free admission) is a block away from the Peabody Library. Three more blocks away is the main branch of the public Enoch Pratt Free Library, which opened in 1933. While not as grand as the Peabody, it’s still pretty neat. The Baltimore Basilica, the nation’s first Roman Catholic cathedral, is right across the street from there. It’s open to just pop into or they have regular guided tours.