From the Pizzagate blog, James Alefantis owned another property in the DC area called the Pegasus Museum.
There was confirmation that they did some underground construction under that building but no idea how big or extensive it was.
This is why the false flag shooter was easy to reveal. Anyone who actually read the blog would have known the 'secret basement' was not under the pizza place.
For those who want to read it, the site is still active.
Original Pizzagate blog.
https://dcpizzagate.wordpress.com/