Grand National in Liverpool expecting 150,000 visitors
More than 150,000 people are expected to flock to Liverpool over the three-day Grand National meeting.
The first day of the festival, Liverpool Day, sees music and comedy from local artists.
It is the first time the meeting has been held since Ginger McCain's death and a bronze statue of the trainer was unveiled in his honour.
Gymnast Beth Tweddle officially opened the event following a sky dive into the racecourse by The Red Devils.
Friday will see the festival's annual fashion parade for Ladies' Day, with the famous John Smith's Grand National Steeplechase being held on Saturday.
McCain's son, Donald, said that having his statue looking down on the winning post would have "meant the world" to his father.
"Aintree meant more to him than anything and to have a permenant reminder here is absolutely wonderful," he said.
Aintree is also home to a life-size bronze statue of Red Rum, the horse McCain guided to three victories and two second places in a five-year period during the 1970s.
Racegoers have been urged to use public transport or local park-and-ride services to get to the ground, with extra trains scheduled before and after the race meetings.
Merseyside Police said spectators faced security checks to get into Aintree and asked visitors "to spare a thought for residents, who accept the massive influx of people into the area with very good grace".
This year is the 165th Grand National Festival.
Forty runners and riders will contest the race over four miles and 30 fences, watched by 600 million people worldwide.