Valley of Pale Death

The valley before you is narrow with a ring of steeper hills rising around it in a tight ring. These peaks are high and imposing, with snow clinging to their jagged peaks. Within this ring there is a a small mound of rock rising from the center of the valley. Perched atop it lies the ruins of a once majestic mountain fortress. Now, even from this distance across the valley, it is clearly falling to ruin.
And yet, the instructions you have been following have led you directly here to this spot.
Moving closer, you can discern the clear passage of feet - shoe, horse, wolf, and other critters. You note that the road which you have been following ascends this hill, gradually winding its way back and forth across the face of the hill, switching back on itself three times. The evidence of foot traffic runs on up the hill on the road. At the first switchback, there is a large hole opening into the side of the hill beyond the turn in the road. You note the road from there to the top of the hill and the fortress is badly neglected, and washed out completely in more than one place. It appears that whatever forces are using this road and this fortress are entering the gaping hole, not traveling to the walled fortress above. This seems slightly odd.
The hole itself, under closer inspection, appears to have been carved out of the hillside far more recently than the construction of the fortress or the road itself. It is crudely excavated, but some attempt at decorative features have been tried. There are what appear to be columns shaped like rampant dragons on either side of the opening. There is also a guardian at the entrance. This guardian is extremely tall, close to eight feet, and terribly misshapen (DC17 Arcana check will recognize this as a flesh golem). It makes no move toward you as you approach on the road, but although it shows no sign of interest, you have the distinct sense that you are being watched.
Background: You are being watched, and how. The golem is paying close attention to your approach, and will react if you move toward the opening itself. In addition to the flesh golem, there are two young remorhaz concealed underground near the entrance. They will join the golem in defense of the entrance.
High in the ring of hills there are many more eyes. There are numerous wolves and some winter wolves roaming above. There is also a young white dragon that feels this valley is its home, so it waits in the snowy peaks and watches. Both the wolves and the dragon stay concealed until the party shows signs of leaving the valley, then they swarm to attack.
This chapter of dragon worship is set up to honor the white dragons of these high mountains. Within the entrance there are 10 kobolds and 4 winged kobolds that will come out at the sound of battle to attack. They are a sentry unit set to guard this entrance, but spend most of their time in their billeting quarters within the tunnel.
The cult came to this location because of the white dragons in the region. They explored the decrepit fortress and found a sprawling dungeon complex beneath it. This appealed to them and inspired them, so they moved in. They have expanded and fortified the dungeons, believing them to be the true heart of the fortress. I need to build a map of the complex, and stock it. There needs to be a more threatening adversary than kobolds. They can have lots of the little creatures around, but there needs to be a significant number of "higher order" creatures running the cult. Something to work out...