Finding things to do in February can be difficult – especially if it is half-term and there are the children to entertain. But here's a chance to combine a day in the fresh air, explore a ruined castle, and enjoy a few hours on one of Britain's best steam railways.

Corfe Castle was once an important military base for soldiers defending the area around the Purbeck Hills from invaders arriving at Poole Harbour.

It's now a ruin – but those ancient stones are steeped in history, and offer a reminder of better days when kings, lords and ladies and local people used it as a sanctuary and called it their home.

It is easy to see from the position of the castle how well it could have served, both as an important seat of power, and to enable archers to fire on invading armies, or perhaps, even throw the odd boulder or two from the ramparts.

Today you can still see the slits in the walls which were used by those archers, and "murderholes" from where various missiles would be launched on unfortunate people below.

Crafty locals moved in when the castle was finally abandoned and removed much of the stone to build a new village for themselves.

When they had taken all they needed, Mother Nature put her own mark on the remains.

So, you now have a combination of an historical site and a nature reserve, which is ideal for a family visit.

In fact, it is more like an adventure playground than a ruin, with slopes to roll down, areas to picnic upon, and exciting places, such as the ancient dungeons, to explore.

And, of course, it is set in some of England's most glorious countryside, with the seaside towns of Poole and Weymouth within easy reach. Children will love playing soldiers on the remains of the battlements, while mum and dad just might like to imagine what life must have been like inside the castle through the centuries, and in whose footsteps they might be walking.

Nearby, you can buy tickets for the famous Swanage Steam Railway, which is holding a family fun week from February 14-22.

Your ticket entitles you to unlimited travel on the trains for a whole day, and there are also vintage bus rides, Twistina the Balloon Lady, and plenty of mouth-watering refreshments.

The event launches the 2009 services of the railway which first came to Swanage in the late 19th century and was operated by the London and South Western Railway Company.

Permission for the new service was granted in 1881 and the first public train left Swanage station in May 1885.

The railway had a long and happy history serving the local community, until January 1972 when, after a huge public outcry, British Railways not only closed the line, but also lifted the entire track – seemingly making it impossible for it to ever operate again.

But such was the strength of feeling that public meetings were called, and a group of enthusiasts decided to take over, and rebuild the line.

People from all walks of life worked as engineers, builders, carpenters and gardeners, and finally got a licence to operate the railway once more.

They not only rebuilt the line, but also restored the disused railway station site to its former glory.

Their work has continued since that summer of 1975, and their efforts are what you see today.

Family fun week is on February 14-22. Tickets for unlimited travel on the day cost £10 for adults and £8 for child aged from three to 15. A family ticket (two adults and two children) costs £30.