Penshaw Monument has been lit up in red, white and blue after yesterday's terrorist attack at Westminster.
The union flag has also flown at half mast at Sunderland Civic Centre today as a mark of respect for those who were killed and injured in the attack on the Houses of Parliament.
Council Leader, Coun Paul Watson, said: "The terrible events in Westminster were an attack on our democracy and it is important that we stand together against such wanton acts of violence.
"People in this country will not be cowed by such evil attacks.
"It is right and fitting that we should show solidarity with our capital city by flying the flag at half mast and lighting up one of the city's best loved landmarks as a mark of respect to those who died and were injured.
"It is also important that we pay tribute to PC Keith Palmer and to the emergency services, medical staff and passers by who came to the aid of all those who were caught up in this tragic attack."