Whithorn has a broad, attractive High St that is virtually closed at both ends (it was designed to enclose a medieval market). There are few facilities in town, but it's worth visiting because of its fascinating history.
In 397, while the Romans were still in Britain, St Ninian established the first Christian mission beyond Hadrian's Wall in Whithorn (pre-dating St Columba on Iona by 166 years). After his death, Whithorn Priory, the earliest recorded church in Scotland, was built to house his remains, and Whithorn became the focus of an important medieval pilgrimage.
Today the ruined priory is part of the excellent Whithorn Timescape.