See the castle ahead? Get ready to invade its mighty walls! Head across the drawbridge, over the moat and up to the top of the tower. Let’s build a brand new one. Whose is the tallest? Can you measure it? Then dig deep, deep down, making burrows and tunnels, just like the animals who live underground. Let's be architects and build bridges. Make sure your bridge is strong enough to take our weight and get us safely to the other side.