Ring of Iron castles

Are you just limiting yourself to the Castles built by Edward I?

There are loads and loads of Castles in Wales and some of the Welsh castles may not be as inspiring to look at as the Edwardian ones, but often win out as far as location is concerned.

Are you planning on just North Wales, or are you intending to do South Wales as well? If planning on both, you will need a bit longer than a week to do the castles (and area) justice.

My favourite castles in North Wales are Conwy, Beaumaris, and Harlech with Rhuddlan just sneaking into the list. I've left out Caernarfon which is a bigger version on Conwy but lacks the interior structures. I prefer Conwy as you get much more of the impression what the castle would have been like. Flint was the first of the Edwardian castles to be built and is intresting as it gives an idea of how the castles developed over time, but probably isn't a must see. There isn 't a lot left of Denbigh Castle either, so I'd be inclined to give it as miss.

Welsh castles you might consider are Ewloe, surrounded by trees (allow 5 minutes walk from the car park) and Dolwyddelan Castle in its splendid isolated setting. There is also Criccieth Castle which was a Welsh castle but rebuilt by Edward.

Further south is the lovely Welsh castle of Castell y Bere on its isolated hill top, again in the middle of nowhere.

South Wales - Cardiff Castle is worth visiting . It was a Norman castle built on a Roman fort. The Marquis of Bute transformed it into a magnificent family home in the C19th. Don't miss the fairy tale Castell Coch on the outskirts of Cardiff. Again this was restored by the Marquis and the interior is stunning. OTT bling just doesn't begin to describe it. Think Arabian Nights.

There is also Caerphilly Castle and also Raglan. Both are big with lots to see and worth visiting.

Check out these websites:> http://www.castlewales.com
https://cadw.gov.wales

In north west Wales, Conwy, Caernarfon, Beaumaris and Harlech Castles can all be reached by public transport.
https://www.traveline.info is a good site for telling hoe to get from a to b.
https://www.traintickets.com/?/ is a good site for finding train travel in Britain.

In addition to the ones wasleys mentioned, almost all of which I’ve visited, in the Raglan castle area are Skenfrith, White, and Grosmont castles. They are not as nice as Raglan but worth stopping at. Then there are Cardiff and Chepstow castles. Further west are Carew and Pembroke castles. The latter is impressive. On both our trips to Wales we had a rental car. In addition the castles we also visited some abbey ruins, Tintern, Neath, and Cymer, as well as some Neolithic sites. There are hundreds of castles in Wales, so you have plenty to choose from.

I also like Carreg Cennan Castle on its marvellous hilltop setting. This is another Welsh Castle rebuiolt by John Giffard, who fought for Edward I. . The problem is there are so many superb castles in Wales, it is difficult to decide which to do...

There are border castles in England
One of the best is at Ludlow but i like the ruined one at Clun in superb unspoilt countryside
As per AE Housman's poem
Clunton and Clunbury
Clungunford and Clun
Are the quietest places
Under the sun
The small town of Bishops Castle is place to stay, although there are little remains of the castle
.There is a ruined castle at nearby Montgomery

Those are some wonderful castles and the Welsh borders is an area that gets few tourists.

It's a pity to OP hasn't been back to let us know what he thinks about the suggestions...

The information about the Welsh-built castles is helpful, because I'd like to take a tour of them, and possibly skip Edward's castles, with the possible exception of Conwy.

There are so many wonderful castles in Wales and you will be spoilt for choice. Don't completely disregard the castles of Edward I as they do illustrate developments in castle building. Conwy should definitely be on the list (and remember you can walk part of the town walls too). Beaumaris with its moat, also deserves to be on the list. It was the last of the Edwardian castles to be built and was the most sophisticated and finest concentric castles ever built.
It was to be Edward's crowing glory and the most impregnable castle ever designed, even though it was never finished as Edward ran out of money.

There is a fun map showing some of the castles here. There are lots more to be discovered!