The Hill Valley Hall of Records was where the city records and documents of Hill Valley were kept.
On March 3, Marty McFly and Jennifer Parker received a letter written by Clara Brown in 1893, saying her husband Emmett had vanished during an attempt to reach the future, and so visited the Hall of Records, where they asked Goldie Jr. for help in finding the location of Doc's second, secret lab where the original DeLorean time machine was built.
Goldie Jr. checked the property records of Hill Valley, but could find nothing under the name Brown. However, when he suggested that Doc may have registered the property under another name, Marty remembered Doc's birth surname was Von Braun, and could have used that instead. Thankfully, it turned out this was the case.