If you have 24 hours to spend in Calderdale, here are some suggestions for things to do:
Shibden Hall is a historic house and park. It's a great place to learn about local history and explore the countryside. You can easily spend around 3 hours here.
The Rochdale Canal runs through Calderdale and is a great place for a leisurely stroll. There are plenty of spots to stop for a picnic or a drink. Walking the whole length of the canal will take around 5 hours.
Hebden Bridge is a small town known for its independent shops and galleries. It's a great place to spend an afternoon browsing and shopping. You can easily spend 2-3 hours here.
The Piece Hall in Halifax is a beautiful Georgian building that has been restored and turned into a cultural centre with shops, restaurants and events. You can spend an hour or two exploring here.
If you're feeling adventurous, head out into the hills and moors around Calderdale, which offer some great hikes and stunning scenery. Depending on the length of the hike, this could take anywhere from 2-6 hours.
With these suggestions, you should be able to fill up your day in Calderdale with plenty to see and do!