Thomas Decatur's Workshop was the workshop where Thomas Decatur worked on his many inventions.
The workshop was first, and so far, last seen in "Jersey Devil". Thomas took Leo and his friends on a friendly tour through the building, which lead to Alebrije almost getting impaled by one of his malfunctioning inventions.
After their hijinks, Baba Yaga, currently disguised as Jacob bulges into the place with an angry mob of Townsfolk and confronts Thomas on accounts of witchcraft and satanism. After destroying his flying machine, the Townsfolk arrest Leo and his friends.
After that is all said in done, the Workshop becomes a base of operations for the Townspeople, now led by Leo in order to fight off the evil Jersey Devil. With the help of the town, the group is able to build a Tank in the image of Leonardo Da Vinci's classic design and drive the monster away for good.