This is an old bug but has been confirmed as still working.
Many house placement tools from years ago, were converted to their current state from house deeds. These tools, and only these old converted tools, will catch the attention of architects at the carpenters shop.
When you walk past those npcs, text will appear about dropping the deed on the npc. This text appears through walls and if you follow the instructions and drop the deed on the npc, you will get the gold value of that old house deed.
It's a great way to get free money.