Unlike a blog, classified sites tend to sell items that eventually are no longer available, and it's almost every page on the site that works like that (except category pages for example) We have 2 options at the moment: We keep the old ad urls. Note that these urls won't be linked from on the site anymore. They will technically only exist in Google's index. When someone comes through to them, they are present with a suggested replacement ad that is currently available. So 5 years from now, most of the "indexed" pages on the site that google sends traffic to will be these pages that simply tell you about another ad. Not nice, but so many classifieds are doing it like this. 301 the deleted/sold/expired ads to a relevant existing ad. Might have scenarios resulting in soft-404s. Both have pro's and con's, but any further insight into the matter will be great!