“CHANGING RULES OF 21ST CENTURY WARFARE: INTERNATIONAL CHAOS.” Thursday, Sept. 19, 7 p.m., Salem Athenaeum, 337 Essex St., Salem. Tom Nichols, professor of national security affairs at the Naval War College, will discuss the new age of preventive war and humanitarian intervention. Admission $15, $10 for Athenaeum members, free for students with ID. www.salemathenaeum.net or 978-744-2540.
MILE MARKERS AND STONE STRUCTURES. Friday, Sept. 20, 7 p.m., Wenham Museum, 132 Main St., Wenham. Mary and James Gage, local authors of “The Stone Structures of Northeastern United States,” share the history and art of mile markers and stone structures that line North Shore byways from Boston to New Hampshire’s seacoast. Book signing will follow the lecture. 978-468-2377, www.wenhammuseum.org.
SLAVERY AND FREEDOM: AFRICAN-AMERICANS IN BEVERLY, 1750-1850. Saturday, Sept. 21, 11 a.m. to noon, Beverly Public Library, Sohier Room, 32 Essex St., Beverly. Illustrated lecture by historian Terri McFadden. Hear story of Beverly’s 18th- and 19th-century black families and what life was like for them, with particular focus on the Larcom-Thistle family. Light refreshments served. Free. 978-921-6062, firstname.lastname@example.org.
SEVEN LECTURES AT SEVEN GABLES: ROBYN KANTER. Saturday, Sept. 21, 2 p.m., The House of the Seven Gables, 115 Derby St., Salem. Garden designer Robyn Kanter will share the challenges, successes and failures of maintaining a historic garden. Follow The Gables garden through an entire growing season, and hear how the gardeners are adapting gardens to a new climate, finding sources for older varieties of plant material, and dealing with new plant diseases. Bring a notebook. Registration and details at www.7gables.org.
“A JEWEL FOR THE TOWN.” Monday, Sept. 23, 9:30 to 10:30 a.m., Beverly Public Library, Sohier Room, 32 Essex St., Beverly. Rockport Music Executive Director Tony Beadle talks about what Rockport Music offers for all ages. Part of Monday Mornings adult lecture series. Light refreshments served at 9 a.m. 978-921-6062, email@example.com.