Wht kind of error is this...? if it even is one. The house in the back looks like it doesn't connect with the the upper portion of it..like its floating.
It's a known issue called a Floating Roof. It is caused by an overpolished Die. That's a nice one even though it is nothing really major. Some collectors don't even consider it an error. I keep them when I find them. By the way.. That's the Lincoln Memorial Building.. Not a house
Here is some information https://www.ngccoin.com/boards/topic/414957-1969-d-penny-floating-roof/ And please.. Ignore any ebay or etsy listings that state they are worth hundreds and even thousands of dollars.. Because they are NOT! Also avoid YouTube videos claiming they are worth a lot of money.
Here is a good read about die cleaning. https://www.coincommunity.com/forum/topic.asp?TOPIC_ID=281951
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