The Shield is a huge rock formation on the west side of the Sandia Mountain range that resembles a medieval shield. See the map above. It's a cool jagged rock face & is the largest rock feature on the mountain. With the sheer walls & pinnacles, it draws rock climbers from all over. There are a few mines & a quarry in the area, too. The Pueblo of Sandia, which owns the land around The Shield, reveres it as a sacred protector of their land. It's easy to see how The Shield seems to wrap around the border of the Pueblo, protecting their watershed.
Which brings us to Piedra Lisa. The Piedra Lisa Trail is a 5 & 1/2 mile hike starting just before Evergreen Hills, skirting behind The Shield, & finishing up in the Open Space at the Village of Placitas. I hiked the trail & one advantage if you're not looking for too strenuous, is that it doesn't go up to the top of the Sandia Crest, but instead traverses behind The Shield; the view scenes to the west & up the mountain were amazing.
The image above was from the La Cueva Picnic Area, gazing west. The Shield starts at the right-hand side of that image. Just below is a map showing how to get to the limited-access communities of Tierra Monte & Evergreen Hills; also how to find the La Luz & Piedra Lisa Trailheads.
Below is the community of Evergreen Hills. The rock backdrop behind the small group of houses is the backside of The Shield.