For my 11th year as a volunteer for Open House New York, I will be stationed at the Masonic Lodge from 10:30 until 2:30 on Sat Oct 12. I had an extensive tour of the premises with the Guides Association of New York (a great site to find me and other private licensed NYC tour guides) a few years ago and it is truly a hidden gem close to Madison Square. I never visited during Open House New York because the I either wasn't in the neighborhood or the lines were too long. You will either find me doing crowd control for the lines or doing the raffle pitch by the donation box at the end of the tour. OHNY needs money to keep the weekend free and open to all.
In recent years, the Masons have become a less secretive organization. They now want people to know about their history and philanthropic efforts. If you are planning to be in the neighborhood, you might be able to take a tour at another time.
The Open House New York program will be on-line at the OHNY website on Oct 2nd and in print in next week's issue of Timeout New York. For some ideas of places that may be on the list this year, have a look at this post from last year. OHNY 2012 review More when the full weekend program is on-line.