LIVE: Second World Summit for Social Development | REUTERS

South Korea's Lee asks China's Xi for help engaging the North | REUTERS

Tanzania's Hassan declared winner in election marred by violence | REUTERS

World's largest cargo sailboat makes first transatlantic crossing | REUTERS

The most polluted major city in the world | REUTERS

Medieval Rome tower collapses with firefighter inside | REUTERS

Hurricane leaves hospital, neighborhoods devastated in Jamaica | REUTERS

Trump says breakthrough trade deal reached with South Korea | REUTERS

Meet the robot that could build structures on the moon | REUTERS