Accompanied by two of her sons, Andrew, 50, and Paul, 52, and family friends, Lady Elsie Robson walked to the Sir John Hall Stand to see the flags, scarves, banners and flowers left there by fans.
A spokesman for the family said she had been overwhelmed by the love shown for Sir Bobby since his death on Friday.
Speaking on behalf of Lady Elsie, the spokesman said: "She is absolutely overwhelmed.
"There must have been thousands of people here and she is very grateful to everybody who has made extremely generous donations to his charity."
Newcastle confirmed the stand at the north end of the stadium would remain open between 9am and 5pm daily next week to allow more people to pay their respects.
A club source estimated that about 50,000 well-wishers had visited the ground since Sir Bobby's death at the age of 76.
Sir Bobby's son Andrew: "As a family we are overwhelmed - really, really overwhelmed - and so pleased to be able to come here and see the [Leazes] End, and all the people milling about.
"It is very touching.
"We are all bearing up very well, really. We kind of expected it, but it is still a little bit of a shock that father has passed away.
"I am sure he would have been very, very appreciative, but I think he would have been overwhelmed and would have wondered where all these people have come from. There's still a queue outside.
"We really have been surprised by the depth of feeling in some of the reporting.
"I think it is a fitting tribute to my father.
"Many people knew him through professional football in one guise or another, but we just knew him as our dad.
"I think he will be remembered around Europe and here at St James' Park, at [Ipswich Town's] Portman Road, the Nou Camp [in Barcelona], and other places where he managed - and we are very thankful for what they have done over the past two or three days - and locally for his charity work as well."