Egypt's Siwa Oasis is about 180 miles (if memory serves) south of the coastal town of Marsa Matruh. In the fall of 1988 I spent about 3 months traipsing around in that neighborhood on a mountain bike, and Siwa made a big impression on me. When Alexander the Great visited an oracle there, he referred to the place as ancient. This is a view of the types of rock formations you see as the road drops down into the Qatara Depression, in which the oasis is located. (I highly recommend googling "Qatara" or "Qattara" or "Siwa" to see what it's like.
While I saw some incredible sights, I'm hesitant to endorse my method of getting there. I suggest you travel by means other than bicycle.