The distance to the center of the Earth from the poles is only 3,949 miles (6,345 km.). The earth is not uniformly circular, therefore, if you went straight to its center from a point on the equator it would be 3,963 miles or 14 miles (22.5 km) further than if you started from a pole location.

In the past, mining and drilling projects have penetrated less than .5% of the distance to the earth's center. Just to penetrate the top layer (the crust) a drill hole would be at least 3 miles (4.8 km) deep, if drilled in the ocean. If drilled through continental land masses it would be at least 20 miles (32.2 km) deep. The next layer is the mantel. You would need to drill 1800 miles (2897 km) more, before you would even reach the outer "core". That point is still less than half way to the center.

Such a "journey to the center of the earth" does not seem possible given current levels of technology. It would also be very very hot!

More Info: en.wikipedia.org