Ipiales is a border town in the far south of Colombia, right on the line with Ecuador. It has the feel of most border crossings — busy, transactional, not somewhere you'd linger by choice. The Rumichaca Bridge to Tulcán is the main land crossing between the two countries, and most travellers pass through quickly in one direction or the other.
The reason to stop is Las Lajas Sanctuary, seven kilometres outside town. Built into the walls of a river canyon, this Neo-Gothic church spans a bridge 50 metres above the Guáitara River. It looks like something that shouldn't exist — an elaborate European cathedral wedged into an Andean gorge. Whether you're religious or not, it's one of the most extraordinary buildings in South America and worth the detour from whatever route you're travelling.