An Islamist extremist called on his friends to "attack" while standing outside London's Royal Festival Hall, a court has heard.
Shehroz Iqbal, 28, is accused of encouraging terrorism by posting mobile phone footage of the "chilling" message to a WhatsApp group.
Opening the trial at London's Old Bailey, prosecutor Kate Wilkinson described Iqbal as someone with extremist views who is “volatile and prone to act in his extremism”.
On March 11, he visited the Hayward Gallery on the South Bank, near the Royal Festival Hall and Waterloo Bridge, the court heard.
He spent about an hour and a half at the popular art attraction and made a video on his phone, it is claimed.
Ms Wilkinson said: “It was a calm video, it was short and its message was clear.
“It spanned from across his vista as he stood there at Hayward Gallery and focused on the traffic passing on Waterloo Bridge, and then he spoke rather chillingly.”
In the footage played in court, Iqbal allegedly said: “This is my spot Akhi (brothers) Central London. Attack, attack.”
Ms Wilkinson told jurors: “The Crown say this was the defendant telling his ‘brothers’, his like-minded associates on his WhatsApp thread, that this place, Royal Festival Hall – Hayward Gallery – Waterloo Bridge, was his ‘spot’, a very public popular attraction.
“To do what? He goes on to say ‘Attack, attack’.”
The court heard that Iqbal posted the video to a WhatsApp group of 22 associates called From Dark To Light.
Ms Wilkinson said Iqbal would deny posing a threat or wanting to encourage people to feel threatened by his acts.
But she added: “The Crown say that when he chooses that is exactly what this defendant wants people to feel.”
She played a second video Iqbal allegedly recorded on the London Underground in September last year.
It showed a man sitting and reading a newspaper while a male voice shouted “racist f****** bastard”.
Iqbal, of Ilford, east London, has denied encouraging terrorism on WhatsApp and disseminating terrorist material on Facebook.
The second charge relates to a propaganda video depicting ISIS fighters in 2015, posted just as the UK went into lockdown in March.
The court heard that the video, which featured an image of a dead body, was viewed more than 200 times on the defendant’s Facebook page.
On his arrest in April, Iqbal claimed he had been high on drugs when he posted the Facebook video without looking at it.
He explained the video at the Hayward Gallery, saying he had gone for a ride that day and made the film to show off his bike.
But Ms Wilkinson told jurors: “The Crown suggest that was a video not showing off his bike but rather saying to his friends ‘Look what I might do’ – carry out an attack in central London in a public spot just like the Royal Festival Hall or Waterloo Bridge, just as others who shared his extremist Islamic views had done before on 9/11, in Manchester and on London Bridge.”