Pasto is the capital of Nariño Department, which is Colombia's most South Westerly department. Most travellers simply pass through coming from or going to nearby Ecuador, but there's actually plenty of very interesting and scenic tourist sites nearby that are well worthy of a few days exploring.
Pasto
Pasto is a pleasant enough Andean city with a few fine colonial era buildings that lies in the shadow of and active volcano. January 5 and 6 sees the annual Carnival de Blancos y Negros, a riotious carnival involving a lot of face painting and drinking - this is certainly one of Colombia's best festivities/carnivals. The rest of the year, there's not a huge amount to do, other than use the city as a base to visit nearby sites of interest or to travel onwards to the border with Ecuador (2 hours away - for safety reasons, avoid travelling this road at night - by day it's safe and is a very scenic journey).
Around Pasto
The best day trip from Pasto is to visit the beautiful lake called Laguna de la Cocha. Boat rides around the lake are good value - the highlight of such a tour is Isla Corota, a small island (and National Park) with well preserved cloudforest and wonderful views. Laguna de la Cocha is less than an hours drive from Pasto and can easily be visited on a day trip (take a taxi from Pasto, or shared taxis depart regularly). There's various hotels here, romantically located overlooking the lake - the best of which is probably Hotel Sindamanoy (website in Spanish only).
Laguna Verde is a wonderful, emerald green lake found in the crater of the extinct Volcan Azufral. Ask locally (try the tourist office in Pasto) about joining an organized tour to this lake.
Depending upon current seismic conditions, you might also be able to climb Volcan Galeras, the active volcano which looms over Pasto. On a clear day, the views stretch as far as the Pacific coast of Colombia.
Ipiales, Santuario de las Lajas & South towards Ecuador
Ipiales is pretty much right on the border with Ecuador - there's no point in staying in this border town unless you have to (border towns are never attractive in South America). The real travel highlight in this area is Santuario de Las Lajas, a church which is spectacularly located in a mountain gorge. Santuario de las Lajas is located just 7km from Ipiales, so taking a taxi costs very little. If you want to avoid Ipiales altogether, there's also shared taxis that leave from Pasto (about 2 hours travel time). If you want to spend the night in this area, there's a few hotels located next to the Santuario (hence no need to spend the night in Ipiales).
It's a short and simple hop from Ipiales over the border to Ecuador and the town of Tulcan. If travelling from Ecuador into Colombia, in Ipiales there's a large and modern bus terminal with buses to Pasto (2 hours travel time), Cali (10 hours) and Bogota (25 hours) as well as other destinations. Remember, it's not particularly safe to travel North between Ipiales and Pasto late at night (due to bandits rather than guerillas).
