Tregothnan Gatehouse - Tresillian Extending over 40 hectares, the Tregothnan garden is the largest historic garden in Cornwall. The collection of plants, is highly regarded in the botanic world. 2 Rate Location Truro Truro Go to website » 01872 520291 Attractions near Tregothnan Estate St Mawes Castle Pendennis Castle Trelissick Garden Lost Gardens of Heligan Trewithen Gardens Penrose Water Gardens