Thousands of visitors are expected at the event over the next three days
The three-day Grand National festival has been declared open.
About 150,000 people are expected to attend the event, which was opened at Liverpool's Aintree Racecourse by actor Ricky Tomlinson on Thursday afternoon.
This year, the first day of the event is being called Liverpool Day, with music and comedy from local artists.
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.
On Thursday, racegoers will be entertained by former Cast and The La's front man John Power, tribute band The Bootleg Beatles and Liverpool band 6ix Toys.
The Beatles' Story waxworks, originally from Madame Tussauds, will be on display and people from The Beatles' Story dressed in Sergeant Pepper suits will be at the site.
Ricky Tomlinson, famous for his role as Jim Royle in The Royle Family and also his role in Brookside, opened the festival at 1340 BST.
Ricky Tomlinson opened the festival
He said: "If any city on the planet deserves to be commemorated, it is Liverpool.
"The Grand National is a time for Scousers and people throughout the UK to celebrate everything Liverpool has to offer.
"Liverpool Day is just the start of what promises to be a fantastic three-day event."
Visitors are being urged to use trains, taxis or local park-and-ride services to avoid traffic delays in the area around the ground.
Merseyside Police said spectators faced security checks where necessary to maintain their "excellent record of deterring crime and anti-social behaviour" at the festival.
Four people were arrested on the first day, all outside the ground, for offences including criminal damage and theft.
Ch Supt Ian Pilling, of Merseyside Police, said "Today's race-goers seemed to have had a fantastic day and the festival has off to a great start.
"Everyone has left a smile on their face, with no trouble inside the course and only a handful of arrests.
"We are reminding Ladies Day race goers to get to the course in plenty of time to get through the necessary security checks, otherwise they risk missing the start of the racing programme.
"We are also reminding people not to turn up to the course drunk, as they will not be admitted."
A giant pink handbag will greet race-goers for Ladies' Day.
It has been put in place by police to remind visitors of steps they can take to avoid falling victim to thieves.