The White Sanitarium
Better known as the "Old Insane Asylum," The White Sanitarium was home to a few radical medical procedures in the early 1900s that may have lead to the death of a few patients -- and legend has it, those patients' spirits still live on the property. A woman in white was once seen roaming the exterior of the building, and some have reported seeing a group of men playing cards around a table in the front yard. There's definitely no way those could've been real men playing cards, though... ghosts are the only logical explanation.
Editor's note: This building is now a private residence, so you shouldn't really go snooping around. We're in Texas, after all.