Were inclined runways ever under consideration?
Yes, it does work, but cannot really be called practical.

The first reason is wind: It helps to take off and land with a headwind. If the runway slope is on one end, this has to be the end where the take-off run starts and where the landing run ends. Since both are in the same direction, this scheme now needs twice the runway length, the first half for landings and the second half for take-offs.

The next reason is the magnitude of what can be saved. The energy from the height change $∆h$ can be translated into a speed gain $∆v$ by this formula: $$∆v = \sqrt{2\cdot g\cdot ∆h}$$

Let the ten stories be a height of 40 meters, and your speed gain is only 28 m/s. This was significant in the age of propeller aircraft, but jets need much higher speeds to get airborne - 150 knots or more. In sane units this is 77 m/s, and since the energy is proportional to the speed squared, the 40 m slope will save only 13% of the energy needed for take-off. It is simply not worth it.

Now look at the operational consequences: The landing has to be performed such that the aircraft has slowed down to 28 m/s when it reaches the foot of the slope. If it is still too fast, it will overshoot and roll down the other side, and if it is too slow, it needs to run up the engines in order to climb up the slope, expending the energy it hopes to save at take-off.

No, practical is not what I would call this.