Since the existing patio is on a granular base (as opposed to solid concrete) I would absolutely, positively NOT consider any mortared work on top of it. The reason is that the earth is a flexible surface. Though it moves so slowly you can't see it, it is doing it nevertheless. If you were to mortar flagstone or thin brick on top of it, this work would effectively be only as thick as the mortar that glued it on ... 1/2" maybe (?) It wouldn't be thick enough to support itself as the earth underneath shifts. If you're going to mortar something on top, you need a 4" solid concrete, driveway-like base (3 1/2" actual) that will not flex at all. But you could go over it with regular thickness pavers on sand IF you insulate the two layers with an inch of sand. (This is predicated on knowing that the existing base is of SOLID compacted material. Since it's been there a good while, its present shape is a good indicator of how solid the base is.) I would go so far as to say that if the present patio was perfect condition -- smooth, of perfect grade, and all slab joints perfectly matched -- you could go over it without the sand insulation. But it's not likely that it's that perfect. If you go over it, one thing you'll need to pre-plan carefully is the finish grade. It looks like your grade might end up being too high. I don't know what all the holes at the foundation are for, but they're probably not wanting to be blocked. If you need a lower grade, sell all those slabs on craigslist (someone would probably love to have them ... they look like step treads, BTW) and build directly onto your already existing base.

You know, it's interesting how when we travel to Europe or other parts of the world where we can see buildings several hundred years old, we appreciate the patina of age on things -- plaster showing its age, cracked stone paving, irregular color in brick, time-worn marble, and so on. In the US we always want to rip out the old, solid materials because of minor imperfectons, and replace them with something shiny, new, and not necessarily of equal quality. If there is a real problem with your tiles -- undermined and unstable surface, safety issues, water leaks, or whatever -- sure, replace them. But otherwise the older material has charm that pavers do not have, in particular with your nice brick wall and balusters. You'd want all your architectural elements to be speaking the same language.

Kalevi - That's exactly what I want to do in my new house with pavers! I love it! I'm moving from a large yard with 2, 1000 gal ponds and assorted other water features to a much smaller yard. I certainly still will want a pond and plan one like yours. Thinking about 18" below ground and 12" to 18" above. Same shape because I will back it up to a garage on the long side. A couple of questions: Does the paverwork go all the way down below ground level or can I dig down and line the below ground portion and start the paverwork at ground level? What would be stronger? ANyone else who has done something like this, feel free to join the discussion!

Where I live there is (or was, they either moved or quit) a business that fabricated concrete steps for house trailers and the like and just about anything you could imagine in concrete. Many of the products sold retail for very little more than you'd pay for materials for a small job. But, goodness, this stuff is a bear to manhandle and you can't talk "cheap" in the same breath as 180 feet of anything. It may not be the look you seek, but one of the products I see used along highway lengths of rural lots is a concrete post with three diagonal square openings to hold 4x4 or 6x6 lengths of wood making long, 3 bar fences and usually painted white, wood, concrete and all. Check with your local building authority. Many of us can find ourselves with an expensive demolition job when it isn't allowed or to code. In today's paper a judge was totally disinterested in a man's plea of ignorance. Let us know your ultimate solution and we sure appreciate photos! David