This year's London Marathon will take place on a closed-loop circuit around St James's Park on 4 October.
The event, moved from April because of the coronavirus pandemic, is restricted to elite athletes, who will be in a bio-secure bubble during race week.
The finish line will be in its traditional place on The Mall, with no spectator access to the course.
"We are confident we have created the safest environment for everyone," said event director Hugh Brasher.
"Sports fans all over the world are eagerly anticipating these great races in this unique environment."
The revised route will feature 19.6 laps, taking in The Mall, Horse Guards Parade, Birdcage Walk and the spur road running adjacent to the front of Buckingham Palace.
In the women's race Brigid Kosgei of Kenya, who beat Briton Paula Radcliffe's long-standing world record in Chicago last October, will also be trying to defend her title in London.
British Paralympic great David Weir will be aiming for a record ninth win in the men's wheelchair race, with course record holder Manuela Schar attempting to follow up her 2019 win in the women's wheelchair race.
Athletes will be tested for Covid-19 four days prior to travel and again on arrival at a hotel outside London, which will be used exclusively by athletes and support staff.
Testing will continue at the hotel until the Friday before the event. The hotel was chosen for its 40 acres of grounds where athletes will be able to train during race week.
It will be mandatory for everyone inside the bubble to observe social distancing rules and wear face coverings.
The BBC is planning eight hours of live coverage of the event.
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