Ben Venue (2,385 ft) is the more difficult climb. It starts from behind the Loch Achray Hotel and is waymarked, but it's a strenuous climb which requires hill walking experience, proper clothing and all the usual safety precautions. Allow about five hours for the return trip. Ben A'an (1,520 ft) isn't a giant of a hill, but it's a steep climb from the start, from the car park of the former Trossachs Hotel (now a timeshare development) on the north bank of Loch Achray, and there's a bit of scrambling involved near the summit. It takes about 11/2 hours to the top. The views from both hills are stupendous on clear days, but remember that the weather is as unpredictable in the Trossach mountains as anywhere else in the Highlands. A useful guide is Collins' Walk Loch Lomond and the Trossachs.
Both these mountains lie within the Queen Elizabeth Forest Park. This vast and spectacular wilderness of 75,000 acres borders Loch Lomond to the west and incorporates Loch Ard, Loch Achray and Loch Lubnaig, as well as Ben Venue, Ben A'An and Ben Ledi, which overlooks Callander. The park is run by the Forestry Commission and is criss-crossed by a network of less difficult waymarked trails and paths which start from the David Marshall Lodge, Queen Elizabeth Park Visitor Centre, T01877-382258, Mar-Jun, Sep-Oct daily 1000-1700; Jul-Aug 1000-1800; Nov-Feb 1000-1600, parking £1, about half a mile north of Aberfoyle on the A821. The centre incorporates audio-visual displays on the park's flora and fauna and information on the numerous walks and cycle routes, a restaurant and children's play area.