More than 2,000 people are due to line up for the Boston Marathon on Sunday.
The 26-mile (42km) race – described as the flattest in the country – will start in Market Place at 08:00 BST.
The route will wind along narrow country lanes and through villages before finishing at Boston College.
Hundreds of runners will also take part in a half marathon and 5K and 10K races.
Organisers encouraged spectators to gather at six points along the route to offer their support.
They include vantage points in and around the villages of Butterwick, Bennington, Leverton, Wrangle and Fishtoft.
A spokesperson said: "Because the marathon route cannot be crossed we recommend spectators approach the lanes from roads branching off the A52 and park on these approach roads before they meet the route."
The half marathon will start at 08:30.
The 10K race will start at 08:15 in Central Park, with the 5K following at 08:45.
Race director Kay Bonnell has been planning the event for nine months and said she was really excited "to get it [the race] on and watch the runners come through".
She said there were runners from overseas and across the UK hoping to set a time that would help them to qualify for marathons elsewhere.
Road closures
There will be restricted access to the Market Place between 07:00 and 10:00 while the runners set off.
There will also be speed restrictions in place throughout the course, with a road closure between Eastwood Road and Skirbeck Road up to Skinner's Corner.
The marathon's chosen charity of the year is the Lincolnshire Emergency Blood Bikes Service.
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