Flags were at half-mast in Nottingham and Derby on Monday following the death of Brian Clough.
Forest fans have laid flowers, shirts and scarfs at the City Ground
Clough won back-to-back European Cups at Forest and reached the semi-final with Derby, leaving his indelible mark on both cities.
Fans flocked to Forest's City Ground and Derby's Pride Park to pay their respects to the football legend.
Both clubs have opened books of condolence and are planning to hold a minute's silence in his honour.
Forest fans were invited by Nottingham city council officials to pay tribute to their hero by signing a condolence book at council headquarters in the market square.
Clough, who died aged 69, was made an honorary freeman of the City of Nottingham in March 1993 to salute his service to the city as manager of Forest.
Forest confirmed there will be a minute's silence at their Carling Cup game against Rotherham on Wednesday and their Coca-Cola Championship clash with West Ham on Sunday.
Officials at Pride Park called on Derby fans to suggest a fitting tribute to their hero.
Fans have laid flowers outside the stadium main entrance in memory of Clough and there will be a minute's silence ahead of the home game against Wigan this weekend.
Derby Council have also opened a book of condolence at Pride Park Stadium's West Stand reception and at the Council House in Derby from tomorrow morning.
Officials from the club have asked fans to email their suggestions of a tribute in appreciation of Clough's work.
The Football League are yet to decide on a fitting memorial for Clough.
The Clough family will hold a private family funeral and that a memorial service will be held at a later date.