A RING of steel has been erected around London's landmarks in the wake of the terror attack at Westminster.

Metal barriers have gone up around the centre of the capital in a bid to strengthen defences and prevent another attack.

20 Bizarre yellow steel structures have sprung up around central London following this attack. This cage was erected outside Green Park Credit: News Group Newspapers Ltd

20 Tourists are seen by a cage erected at the top of The Mall near Trafalgar Square Credit: News Group Newspapers Ltd

20 Visitors file through a cage outside Green Park and Green Park Tube Credit: News Group Newspapers Ltd

20 A man walks through a cage on Marlborough Road Credit: News Group Newspapers Ltd

20 A woman approaches a cage situated near Buckingham Palace Credit: News Group Newspapers Ltd

20 A cage is seen near St James Palace on Marlborough Road Credit: News Group Newspapers Ltd

20 A yellow cage erected near Buckingham Palace on Birdcage Walk Credit: News Group Newspapers Ltd

20 The anti-terror measure located on Birdcage Walk Credit: News Group Newspapers Ltd

20 A ring of steel is being erected in central London in the wake of the Westminster terror attack Credit: Splash News

Four people were murdered in an attack on the Houses of Parliament on Wednesday night when a terrorist launched a terrifying car and knife attack.

Khalid Masood, who was shot dead by a policeman, mounted the pavement on Westminster Bridge mowing down pedestrians before stabbing PC Keith Palmer to death at the gates of the palace.

20 Landmarks around the city have been surrounded by fortifications following the attack on Parliament Credit: Splash News

20 The steel walls line Green Park and the entrance of The Mall which leads to Buckingham Palace Credit: Splash News

20 A truck was seen unloading the barriers around the centre of the city Credit: Splash News

20 Workman worked throughout the night to reinforce the capital following Khalid Masood's murderous rampage Credit: Splash News

Additionally bomb proof cars known as “The Guardians” and heavily armed police have flooded the streets in the wake of the Westminster terror attack that left four victims dead.

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The number of cops have almost doubled around London and throughout the country after terrorist Khalid Masood drove his car across Westminster Bridge, ploughing through crowds before stabbing a police officer.

20 The news comes days after concrete barriers were seen being taken into Westminster Credit: Splash News

20 Armed police officers stand at the Carriage Gates entrance to the Houses of Parliament, following the attack in Westminster earlier in the week Credit: Reuters

20 The huge vehicles are complete with bars on the front to punch through barricades

20 A police officer can be seen standing in front of a heavily-armed vehicle Credit: Getty Images

Part of the response to the terror attack includes huge seven-tonne cars that can withstand bomb blasts and machine gun fire put onto London's streets, with the vehicles able to plough through barriers.

The huge Jankel armoured vehicles, manufactured in Weybridge, Surrey, include a V8 turbo-diesel engine, as well as with bullet proof glass and tyres and bulletproof glass.

The heavy-duty machines, known as "The Guardians" can also punch through barricades while being fully protected with blast resistant floors.

20 Floral tributes were laid at an anti-Brexit march by pro-EU protesters Credit: Getty Images

20 Police have doubled their security on the streets, vowing that London would be open for business Credit: Getty Images

20 The streets have been inundated with armed police Credit: Reuters

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