Malaga What is open on Sundays?

The market is closed on Sundays.

Fans842,

The Cathedral is also closed on Sunday.

The Roman Theater is open on Sunday, but closed on Mondays.
The Alcazaba Fortress is also open on Sundays.

Hope this helps ;-)

For future reference, the websites of most sights indicate the hours they are open each day. Generally they'll also specify exceptional situations, like closures for Easter, Christmas, etc. If there's something I want to be sure of seeing in a city I'll visit for only one or two days, I always double-check on the Internet ahead of time, because guidebooks don't always have the very latest information.

You can't always trust the websites for lesser sights, as I found out to my dismay when I was in Malaga in March last year.

You didn't mention art galleries in your original post, but the Picasso and Carmen Thyssen Museums, Pompidou Center and the Contemporary Arts Center are among the many excellent museums in Malaga, and all are open on Sundays. Also, I visited the Cathedral on a Sunday during my October 2016 trip.