Calc: how find & display cell which contains longest string in column in spreadsheet in terms a1

[morphingstar]

how find cell which contains longest string in column in spreadsheet terms a1.
I am using the array {=MAX(LEN(A1:A999))} which finds the longest. I would like to display the cell reference above the column “a1” as to which cell contains it. if there are several the first cell closest to cell a1 would be fine.
the actual formula is {=MAX(LEN(D11:D500))}
tks

[fpy]

@morphingstar

column “a1” as to which

{=ADDRESS(MATCH(MAX(LEN(A:A)),LEN(A:A),0),1)}