L'Invincible

Reads initially like the sort of traditional science fiction you might see on TV - rocket lands on foreign planet, sends out teams to discover what gives. what follows is a gripping scientific detective story as we learn the terrible secrets of a past race, and Lem takes us on a journey of wonder and awe. Reminiscent of the final passages of HG Wells' Time Machine as the author shows us beings and worlds we could never imagine. I've read this several times and will read it again and you should too.