This isn't a story about the largest house, but it's a good one for fairly recent (last 40 some odd years) Marin history buffs. When I grew up on Round Hill Road in Tiburon, (our family moved there from near where the Cove Shopping Center is in 1958) there were originally only eight other homes in the "Rolling Hills" and "Red Hill" neighborhoods. A pair of horse grazed on the lot nearby the house my dad designed and built in 1958, (for $27,000!) but the "boomer" era was on the way. Within the next ten years, dozens of homes and apartment buildings sprouted up all around us, including many with kids my age. My dad was an architect, so I always associate that time with the smell of sawdust and paint, and the sound of hammers and automatic saws, as we were always visiting home building sites. One of those homes was just up the street, a very nice and fairly large home of about 4 bedrooms and three baths/ This two level house, with a very nice garage, but no other real amenities, was located just at the right bottom entrance of the road that led up to the three Moulin residences (built in the early 1960s) in the shadow of Mt Tiburon. The place was referred to by Real estate agents as "the House of Spring," and I remember my friends and friends' parents all being shocked at the ridiculously high cost: $100,000! Of course this was way back in 1964, and $100,000 was considerably more than many houses in the area were then costing. And also, this was well before the horrid "McMansions" as I like to call them, desecrated beautiful Mt Tiburon. There are actually some very striking homes in the area that were built further down the hill in the late 1960s and early 70s, but those god-awful monstrosities that now grace (if you want to call it that) the wonderful hill and ridge that we used to hike to and camp out on is hardly accessible anymore. There is no open space, and you're discouraged to take a drive to the top of the Mt Tiburon, making it virtually impossible for anyone to enjoy the spectacular bay views unless you know someone who lives in those palaces. Dear old Mr Moulin, who lived to be 103 (my first job at age 14 was working for him as a gardener. planting trees and watering) told me about ten years ago when I visited him at his home (he was then about 97), that "I did pretty well when I sold that property, Huh?" with a twinkle in his eye. I liked the old fellow too much to tell him what I really thought of his legacy! Actually, my dad, who was the first Tiburon Planning Commissioner back in the mid 1960s, told me recently that Mr Moulin had originally wanted to cut up the parcels up in much smaller sizes and put up a bunch of smaller homes, kind of similar to the "ticky-tack" little boxes that have covered Daly City for many years. That actually might have been a worse scenario, although either way, there would still be no or little public open space. The only real open space now in the Tiburon Hills, (besides the Ring Mountain area) near Bel-Air, which is fairly close to Mill Valley and abuts Corte Madera), is the area above historic old St Hilary church near "the Spanish Trail." That's still a great spot for a quick walk or a picnic!

That is an excellent question, and I have no idea. I can guess that it would be way up out of the way of public view, where no one would even see it being built. The mansion at the top of Fern Canyon Rd. in Mill Valley is guite large but not new. I was walking on the old railroad grade above Blithedale canyon in 1991 and saw a huge house being built, but I haven't been there for a long time. Also out in Nicasio there are some big places that only be seen from the air or on private driveways. And in the unincorporated areas near Novato, (Wild Horse and Indian Valley) there are some newer mansions . Maybe a real estate expert (Jason ?) might be able to answer that one, and also the most expensive house, not necessarily the largest. I would guess the most expensive would be in a place with bay, Mt. Tam and/or ocean views, so that would exclude Novato, probably Belvedere or some place in southern Marin.