The one-space mausoleum is one row above and four spaces to the left of Ms Monroe’s final resting place at the Pierce Brothers Westwood Village Memorial Park and Mortuary in LA.

Run by Julien’s Auctions, the sale is part of a wider auction of Hefner’s and Monroe’s belongings, including Monroe’s first Playboy magazine cover from 1953, Hefner’s burgundy smoking jacket and silk pyjamas, and an orange-hued Elizabeth Arden lipstick owned by Monroe in the 1960s.

The crypt has a starting bid of $50,000 (around £40,000), though the auction house estimated it will reach at least quadruple that price, CNN reports.