As you might know Santiago de Chile is located in a basin and surrounded by certain mountain ranges. Trekking possibilities are well known as well - one certain hiking trail, Im going to explain in the following lines, goes up the "Pochoco hill".
Although it is nice to stay longer in bed on a weekend or public holiday, I recommend getting up early and take the subway in Santiago to the station called "Manquehue", almost the last one of the red line N°1 in the district "Las Condes".
Outside the station one has to catch a public bus (C01) to the square "Plaza San Enrique", where you have to catch a special taxi with a fixed route called "colectivo" to the hill "Cerro Pochoco". The price per person for using the subway and the public bus is less than US$2 - it is just necessary to buy a "BiP-card" you can buy and charge at the ticket offices and use for the subway and public bus system.
The cost for the "colectivo" is a little bit more than US$2 per person. If you arrive close to the foot of the "Pochoco hill", ask for the drivers number to call after your hike to be able to get back to the "Plaza San Enrique" to catch another public bus and subway afterwards.
The entrance to the hiking trail is for free.
The first part of the trail is quite steep and I recommend going up slowly pausing from time to time. The views are really beautiful and you will be enjoying taking a lot of amazing pictures of the Andes Mountain Range, the Coastal Mountain Range and the city of Santiago de Chile. The best time to go up the hill is between late-autumn and early-spring (May - Septembre). On a sunny day one is able to enjoy seeing the mountains full of snow. During summer time in general the trails are more crowed and temperatures are much higher. It takes 2-3 hours to get up the hill and obviously much less to go down again. I recommend anyways to be careful as some parts are really steep and can cause falling down forewards. The hiking trail of "Cerro Pochoco" is a great alternative for those who love doing sports outside, get some fresh air and see the city from another view. Having a tasty beer afterwards helps to forget the fact that you woke up early in the morning.