A hidden treasure only 100 meters from the Xisi subway center in central Beijing is the Pagoda of the Old Man Wansong, or if you want to translate literally, the man of 10 thousand pine trees. The pagoda was named after Wansong Xingxiu, a very famous monk that lived from 1166 to 1246. For those of you calculating, he was 80 when he died.
This construction was made as a tomb for the man, and has been in this same place since he died, making it 770-years-old in 2016.
By the late Ming dynasty the pagoda was already hidden amongst the streets and buildings of the flourishing commercial city of Beijing, and it was not until 1606 that a monk called Le'an (樂庵) noticed the overgrown pagoda, and raised money to repair it. - Wikipedia
Well, in the years since 1606, just like unkept grass in a field, the city has grown back and the pagoda is lost in between the buildings and shops.
The building has undergone several restorations and in 1753 a brick pagoda was built around the original. During maintenance in 1986 workers discovered the original pagoda was still inside, hidden behind the bricks, waiting to be seen.