Hi kishAnSL. Why would you not go by road to Punamarca Ruins? I thought of taking taxi to within a half hour walk so as to have more time.
That's fine. It should be a nice walk. But do leave some time and energy to go up the hills and terraces, which is a steep climb. From up there, there are also trails to hike around.
You can approach by road, but to really enjoy the ruins, you need to hike up into the hills, especially for the views of all the ruins, terraces and grain storage buildings.
There are many ways to do this. You can take a taxi, go up and look, then take the taxi back, but I think that the hike along the upper trail was more interesting than the ruins themselves. If you don't want to walk both ways I would take a taxi there and walk back. See my blog for all the options and complete directions: savvyexploring
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