Trip to Cordoba for several days. Day trip to Castillo de Almodovar possible?

Maps is showing a 40 minute bus (M-250 Rivero De Posadas), verify info at https://siu.ctco.es/tarifa.php.
Then you can get a guide at the castle: https://castillodealmodovar.com/en/

Looks fantastic, I've bookmarked for my next visit!

I’d just take a bus. I don’t think a tour is necessary. Since it shouldn’t take an entire day to visit consider visiting the nearby Medina Azahara. It’s between the castle and town.

I went to Spain in March of this year, 2022. I spent two nights in Cordoba, a Saturday and Sunday nights. Maybe the exact days of the week won't matter for you. Except that many places in Cordoba are closed on Mondays. But Castillo de Almodovar was open on the Monday I was there. After checking out of my hotel, I was close enough to the bus station to walk there; at the bus station I put most of my stuff in a locker. There is a cost for the lockers. I took the bus to the Castillo de Almodovar. It was raining intermittently. There were no waiting tour guides. I don't remember if there was an audio guide available. I spent under two hours in the castle. It was easy enough to take the bus. Yes the M-250 bus towards Posadas has a stop in the town of Almodovar del Rio. In Cordoba you wait for the bus at a spot along the outside wall of the bus station. You pay the driver when you get on. There is a bus stop close to the bottom of the hill the castle is on. You might have to press a button or pull a lever on the bus to signal the driver to stop, or maybe when you get on tell the driver "Yo quiero bajarme por castillo de Almodovar del Rio". On the way back I picked my stuff up from the locker and made it to my train to Madrid 20 minutes before it left. My trip to the castle was easier than I feared. This a perfectly doable day trip.

Thanks Mike, very helpful information!