Bath to Caerphilly and Castell Coch Day Trip

You are in luck as both have a bus service. Checking the Castell Coch website it recommends catching either the 26 or 132 bus from Cardiff to Tongwynlais. It will take about 20 minutes on the bus. There are more detailed directions for the 132 service [here][4]. (Tell the driver where you are going and ask him to tell you where to get off. The drivers are usually very helpful).

After visiting Castell Coch catch the 26 bus to Caerphilly - another 20 minutes.

Take the 26 back to Cardiff .

The two castles are completely different and you can't compare them. Caerphillly is a ruin. Castell Coch was restored by William Burges for the Marquess of Bute and is wonderful inside - think of an Arabian Nights fantasy. From the outside with its turrets it is everyone's dream of what a medieval castle looks like.

That is an interesting question which I thought would be be hard but Traveline Wales saves the day.
[Note that the Castle website says that Bus 26 serves the Castle, it doesn't except on Sunday and early morning and early evening on a weekday, timetables have just changed- it's a shame as that bus ran from Caerphilly thus saving the below dog leg back into Cardiff)

1. Train Bath to Cardiff Central at around xx.40- journey 1 hour 5 minutes;
2. Train every 15 minutes to Caerphilly, journey time 20 minutes;
3. Train back to Cardiff Queen Street
4. Walk to Greyfriars Road Stop GF- catch Bus 132 to Maerdy, as far as Tongwynlais Ynys Bridge, every 15 minutes, journey time 30 minutes
5. 0.6 mile walk
6. Return to Cardiff on bus #132, walk through the City to Central Station, return to Bath.

That is the bare mechanics of the journey on public transport.

Others can answer the rest of the query.

Thank you Wasleys and isn31c - a wealth of helpful info. It sounds tiring to do both in one day....The images of Costell Coch are gorgeous, especially the forested setting. I wonder if there are walking trails around it to extend the experience....

We had a car, so it was easy to see both in a day. As to which to see if you can only see one, castle Coch is a reconstruction, is smaller, and off by itself. Caerphilly is much larger, is pretty much in original condition, and the town is right outside the entrance. Castle Coch is closer to Cardiff, but they really aren’t that far from each other.

The forest to the north of Castell Coch has a series of way marked routes. Have a look at the leaflet here There is additional information here.

Castell Coch is wonderful and completely different.

If you want to go to Caerphilly Castle, I would suggest that you purchase a return ticket from Bath to Caerphilly. On arrival at Cardiff Central - transfer to platform 6 from which the trains to Caerphilly usually depart every 15 minutes (less on Sundays - so avoid). These local trains might be going to Bargoed or Rhymney. The journey to Caerphilly is about 20 minutes. On arrival at Caerphilly - go to bridge and turn R and walk down the miserable main street and you reach the castle in about 10 minutes.

You will want to see Cardiff on return. Show ticket at barrier to staff and say you are having a break on a return ticket - which you are allowed to do.

It is regrettable that you are not staying in Cardiff as there are 4 very different castles in the area = Cardiff, Caerphilly, Castell Coch and St.Fagans = Cardiff Bus 32. Plus of course everything else to see such as the bay, city centre & museum. (The Cathedral is at Llandaff - 2 miles NW of the city centre).

See you tube video of Cardiff but note that you will find far more people than you see in the film.
https://www.youtube.com/watch?v=JiY5qFb3p6U

When are you planning to visit? You should try and avoid events in Cardiff as it can get packed with fans for sport or pop events.

James and Wasleys, many thanks for your suggestions and info. Very much appreciated. As far as a base, we chose Bath because we are familiar with it and have stayed in an apartment there we liked. It's high stakes to pick and choose where to go because, in our situation, we have limited time and resources and are overwhelmed with all the choices. Looking into day trips from Bath (no rental car so will take a train or get a driver). Considering the Castell Coch and Caerphilly (after reading about it on the Wales forum). Also considering a day trip to Salisbury Cathedral (not Stonehenge) and Salisbury museum. Maybe Stourhead or some other manor home in the vicinity. We enjoy art and architecture, gardens, and walks in nature. Moderate hiking and biking. Don't like big cities. Perhaps we will do Cardiff as a base another trip. We will be going up to northwest Wales and use Conwy as a base at the end of this trip (maybe a day for Conwy itself, a day for Bodnant Gardens, and a day for either Llandundo or some place in Snowdonia. Again, no rental car so just trains and taxis for us. Definitely adding Chester in as well for a couple of nights prior to Conwy. Suggestions for day trips highly welcomed. We are overwhelmed and really don't know what we're doing. Just giving it all our best guess. Thanks everyone for helping us.

Stourhead - there is another forum thread on the difficulties of getting there by public transport- https://community.ricksteves.com/travel-forum/england/london-to-stourhead-national-trust
The instructions on their website are so vague as to be meaningless. In practice you have the better part of a one hour walk from a bus stop which has pretty infrequent service.
In reality it is a pre booked taxi from the railhead.