The geocache (and HWY 71 bridge) is located in the area of what used to be a 3 story castle built by Robert Robson, a Scottish settler. It was built entirely out of native limestone. Running water was sluiced up from the Colorado River and available throughout the building. In it's later years, long after Mr. Robson passed and after the Civil War the building was used for as a slaughter house, meat market and ice house.
There is an official Historical Marker near GZ. It dissappeared when the new bridge construction started in 2018 and the city reerected it in a new spot in 2024.
Directly across the Colorado River from GZ is a public canoe/kayak launch site for the Texas Parks and Wildlife Texas Columbus Paddling Trail. The trail is an easy 6 mile journey along the Colorado River to the take out down river at Beason's Park (another part of Texas history).