I went on a short excursion to the outskirts of La Paz to visit Valle del la Luna (Valley of the Moon). Extremely strange and beautiful rock formations; I’ve really never seen anything like them anywhere else.
Any local tourist agency can arrange a trip. I actually combined it with a visit to Chacaltaya, which I understand is a pretty standard “package”. Valle de la Luna itself is only about 20 minutes from downtown La Paz, depending on traffic, and probably doesn’t warrant more than an hour on-site, but definitely don;t miss it.
(Not pictured here is the world’s highest-elevation golf course, which is right next to the Valley.)