The Birthplace of Jebediah Springfield is the house where Jebediah Springfield was born.
When Homer was the conductor of the Springfield Monorail, he used an anchor to stop the monorail. The anchor cut down the Springfield's Oldest Tree, which caused it to timber and fall down on top of the Birthplace of Jebediah Springfield, destroying it in the process.
Another Birthplace of Jebediah Springfield existed in Springfield, but it was built differently and was destroyed again when Moho House got dropped on top of it. Later, the birthplace was rebuilt after Moho House collapsed and got destroyed.
Behind the Laughter
It is unknown which birthplace was Jebediah Springfield actually born in. It could possibly be the new one, since it was at first destroyed, then was rebuilt after Moho House collapsed. The old one is not possible, since it was destroyed by the tree, and the remains of the old one were either reused for something else, or were used to build the new one.