Go to the Library. When Lara walks in the doorway, there are two bookcases to the right. Approach the one on the left and press Action. Then, Lara will pull a book and the fire will extinguish, allowing her to climb up the side wall inside the fireplace. After reaching the top, follow the passageways until reaching a room with two levels, with a switch on the top level. Pull the blocks in a way that a hallway leading into the attic is revealed. When Lara pulls the switch, the basement door will temporarily open. Quickly run through the attic, and down to the main hall to reach the basement. Once in the basement, walk through to the second room and look in the tank on the right side. Inside is the key to the race course. To collect it, pull the block in the other room to the center. Climbing up to the hall that leads into the tank.