At some point I lucked in a desktop blotter that was a pad of 1/4" graph paper. We are talking huge sheets that were about 17" by 22". My first thought wasn't about making a megadungeon.
My first thought was now I can make huge Traveller deckplans :D
Here is one of them a Zhodani Courier from Classic Traveller Alien Book on the Zhodani.