Tower Bridge was shut down after a man climbed up the railings, with emergency services scrambling to the scene.
The individual, who is wearing a grey hoodie and dark trousers, was sat on top of the Grade 1 listed bridge.
The man has since "safely come down", City of London Police said and the bridge will now be reopening.
Witnesses shared footage of the incident on social media, which shows the individual sat on a sloping blue arch
The individual, who is wearing a grey hoodie and dark trousers, sat on top of of the Grade 1 listed bridge
Chrisdyann Edwards
Officers have now said: "The man has safely come down from the railings on Tower Bridge.
"The bridge will reopen shortly. Thank you for your patience."
Emergency services were at the scene, with both police officers and firefighters deployed to the popular crossing after receiving reports of an incident at 10.40am.
Witnesses noted that the individual did not appear to be carrying a flag.
A London Fire Brigade spokesperson earlier said: "Firefighters are responding alongside the Metropolitan Police Service to reports of a person on Tower Bridge.
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Traffic and boats were sat at a stand still
Chrisdyann Edwards
Witnesses have shared footage of the incident on social media
Dale Matthew Hudson
"The Brigade was first called about the incident at 10.40, and firefighters from Lambeth River, Whitechapel, Edmonton and Soho fire stations are at the scene."
A statement from City of London Police read: "Tower Bridge is closed to traffic and pedestrians due to a person who has scaled the railings.
"Please avoid the area where possible. Updates to follow."
Tower Bridge was closed both ways between East Smithfield by Tower Hill and Queen Elizabeth Street.
The individual sat on a sloping blue arch
Dale Matthew Hudson
A pro-Palestine protester scaled Big Ben whilst waving a flag on March 8
PAThe closures led to congestion between Limehouse and Aldgate with buses being placed on diverted routes through the city.
Blackwall Tunnel is also closed due to a separate incident.
The incident comes just two days after another London monument was scaled by a climber.
A pro-Palestine protester scaled Big Ben whilst waving a flag on March 8, only coming down after a 16-hours standoff with negotiators and emergency crews.
The Metropolitan Police has since confirmed that the individual was arrested after being caught.
