If you've got a day to spare in Sydney and you have a car I'd recommend heading northwest of Sydney to visit the charming village of St Albans.
Getting there is easy as you can just drive north of Sydney to the village of Wisemans Ferry where you can take one of the two free Ferries across the Hawksbury River. Depending on the Ferry you took (either will do) you can follow the Macdonald River for 20 kms or so to St Albans. The ferries deposit you onto either side of the Macdonald River and the first bridge across is actually in St Albans. So when you head home, take the opposite side for a new experience!
Once in St Albans you must visit the Settler's Arms Hotel and Pub. It's been there since 1836 when this was the only route north out of Sydney. You can get a fantastic meal and a couple beers or a glass of wine for lunch. There's a wonderful garden out back that will keep the kids happy for hours hiding and climbing in the trees and around the yard. Everything is spread out here!
Once you've had a bite to eat you can visit the local art galleries up the hill, explore the river valley, wander around the village to see the historic buildings and church or all of the above. If you drive across the river you can visit the old Courthouse (now a B&B) to see the old Gaol and historic architecture. On the way home be sure to visit the convict built Old Great Northern Road.
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