The highlands around Bogota offer some of Colombia's most rewarding excursions. The salt cathedral at Zipaquira is the most popular day trip -- an entire cathedral carved into a working salt mine, about two hours north by bus. Villa de Leyva, a beautifully preserved colonial town with a vast whitewashed plaza, makes a perfect overnight escape. Guatavita, the lake that inspired the legend of El Dorado, is an easy half-day trip surrounded by green hills. Tunja, capital of Boyaca department, has fine colonial churches and is a natural stop on the way to Villa de Leyva.