Ascending Pen-y-Fan (886m), the tallest peak in the Brecon Beacons, is one of the most popular hikes in the park (around 350,000 people make the climb annually, giving it the nickname 'the motorway'). The shortest route begins at the Pont ar Daf car park on the A470, 10 miles southwest of Brecon. It's a steep but straightforward slog up to the summit of Corn Du (873m), followed by a short dip and final ascent to Pen-y-Fan (4.5 miles return; allow three hours).
A slightly longer (5.5 miles return) but just as crowded path starts at the Storey Arms outdoor centre, 1 mile to the north. The T4 bus stops here. (Note: the Storey Arms is not a pub!) You can avoid the crowds by choosing one of the longer routes on the north side of the mountain, which also have the advantage of more interesting views on the way up. The best starting point is the Cwm Gwdi car park, at the end of a minor road 3.5 miles southwest of Brecon. From here, you follow a path along the crest of the Cefn Cwm Llwch ridge, with great views of the neighbouring peaks, and then there's a final steep scramble to the summit. The round trip from the car park is 7 miles; allow three to four hours. Starting and finishing in Brecon, the total distance is 14 miles.