i started a megaproject. not hard, but the work to do is big.
an aboveground city, but not a fort or just a city: a city-tower. a huge tower that goes from the ground to the sky. only underground things are stockpiles. at the moemnt it is a building , i'll build a wall around it.
later i'll put a paved road on the empty space to make it inside. the tower is more than 400 tiles. rock walls, wooden floors. i have to cut half map to make only the first floor. and later i'll expand it, when i'll make rock walls (at the moment it is wooden. i had to build a room as soon as i could).
i'll need several thousands of logs, many years and dwarves, a lot of rock (that i get by channelling, so it is still above ground).
what i will get will be a huge tower (about 55x15x15), with the first floor being much bigger because farms, trade depot and brooks are there. houses for all the dwarves (nobles will get a place too... useful nobles will get furniture, unuseful nobles will get a bridge if you understand what i mean)
at the end, i could close the doors, and the tower would still be able to live with more than 100 dwarves inside (don't know exactly how many)
edit: of course there iwll be also elven sieges later. in the first year i cut hundreds of trees!