They (imho) ruined Spitalfields market when it was developed a decade or so ago. A similar large open space market that used to serve indoor independent food stalls; a market and indoor 5 a side football. Half of the market was lost to office buildings and most of the food became chain restaurants. The market does still exist but the overall elegance of the historic building has been desecrated.

I don't know, most Londoners quickly work out that for anything less than 3 stops on a tube line you could probably walk it in less time.

You can walk to Smithfield from the Barbican, Chancery Lane, St Pauls, Blackfriars, Moorgate in less than 15 mins.

There's a new entrance to the Elizabeth line right on the market https://goo.gl/maps/xJ5c4NFaPZeZTQTK9

The different entrances to stations are missing from most maps, and they're important on the Elizabeth line. If anyone knows a map which has them, or knows how to add them to a map (like a layer on OSM/Google), let me know!

I see the one OP mentioned just fine on OpenStreetMap

Farringdon to Smithfield is about a 3-4 mins walk up Cowcross Street, pretty convenient