Valles Caldera National Preserve (a.k.a. what's left of the "volcano that blew a big chunk out of what eons later would become northern New Mexico.")
Vanholio! lured me here by texting that the cellular reception was good and that with my antenna it should be great. He was right. After deploying the antenna my signal jumped from three bars of 3G to four bars of 4G LTE.