As thousands of runners are gearing up for this year's London Marathon, here's a spectators guide for the places to watch - or avoid - the 26.2 mile race.

Starting in Blackheath and Greenwich Park, the route loops through Charlton, Woolwich, Greenwich and Deptford before crossing over the Thames at Tower Bridge.

WHEN

Sunday, April 23.

The main race will start at 10am 

World Para Athletics Marathon World Cup in association with the Virgin Money London Marathon elite wheelchair race will start at 8.55am.

World Para Athletics Marathon World Cup (ambulant athletes) will start at 9am.

Virgin Money London Marathon for Elite Women will start at 9.15.

WHERE

Red start line: Charlton Way

Blue start line: Shooters Hill Road

Green start point: St John’s Parade

WHERE TO WATCH

The race kicks off in Greenwich Park and Blackheath, with three starting points, and the runners will head through Charlton and Woolwich, before loopin back through Westcombe Park and Greenwich.

From there participants will run past the Cutty Sark and through Deptford, before taking in east London and heading towards central London.

Spectators are advised that Greenwich Park, Greenwich Town Centre and Blackheath will be extremely busy on the day of the race.

London Marathon suggest watching the race from Tower Bridge road, near London Bridge Station, to watch runners cross Tower Bridge at mile 12.

Alternatively they suggest walking over London Bridge into the City of London and watching the race as it passes underneath London Bridge.

Another viewing suggestion is to go to Canary Wharf and the Isle of Dogs to see the race between miles 14 to 21.

ROAD CLOSURES

Roads around the route will be closed at 7am on Sunday, and access to and from property will not be possible until the roads reopen at around 2pm.

Any residents who need to leave their houses by car on the day should do so before 7am.

If you have any specific access issues you should call the helpdesk on 020 7902 0200, although the number is not operational on the day of the race.

PUBLIC TRANSPORT

As all the roads surrounding the marathon route will be closed, public transport is the best way to get around on the day.

Southeastern are offering runners free travel to the start lines and are running an extra 111 trains on the day in anticipation of the high numbers of passengers.

Runners starting at Greenwich or Maze Hill should change at Cannon Street only.

Participants beginning the race at the Blackheath start line can change at London Bridge, Victoria, Charing Cross, Waterloo East or Lewisham

London Bridge is expected to be particularly busy from 8am to 8.30am as lots of runners will be changing trains at the station to reach the Blackheath start line on time. 

Runners travel free from London terminals to start lines, but will need a ticket for rest of journey, and are advised to leave plenty of time for their journey.

Spectators should travel later to avoid the race day rush and must have a valid ticket.