Cusco is a blast to walk around, so entertaining the kids and finding suitable restaurants and things to do shouldn't be a problem for most families. Kids old enough to appreciate a bit of history might enjoy the exceptionally laid-out Museo de Arte Precolombino (MAP), as well as the Museo Inka, both of which will give them a good grounding in pre-Columbian civilizations and Inca culture. Beside ceramics and textiles, the Museo Inka displays cool mummies and tiny hand-painted Inca drinking vessels. You'll find Andean women weaving traditional textiles in the courtyard.
Cusco resonates with remnants of the ancient capital; a walking tour with the kids will take you past Inca walls with giant granite blocks that look like the pieces of a giant jigsaw puzzle. Have the kids count the hand-cut angles in the 12-angled stone and find the outlines of the puma stone. Observing the walls will give you a chance to impress your family with your knowledge of Andean history. Explain that the Incas built these massive walls without mortar or cement of any kind and with no knowledge of the wheel or horses, and that they constructed one of the world's greatest empires, reaching from one end of South America to another, without a written language and with runners who relayed messages to rulers.
Another good activity for artistically inclined children is to pop into artists' studios in the funky neighborhood of San Blas. Then walk -- if you have the energy -- up to the ruins of Sacsayhuamán. There you'll find more massive stones and gorgeous views of the city and surrounding mountains, but kids will really dig the huge rocks with slick grooves that make fantastic slides. There are also some cool tunnels cut into stones nearby, which kids might enjoy much more than their parents.
And, of course, the biggest family attraction of all lies beyond Cusco: Few are the kids who aren't fascinated by the ruins of Machu Picchu. The easygoing towns of the Sacred Valley are also great spots for families.
