This level design I made during my 4 years at Titus Interactive Studio was quiet a mess to re-open years later. I went through a Collada export to fix most issues, but some Material IDs and of course all Smoothing groups were lost along the way. I hope you'll excuse those errors (I fixed many) and will still find this mesh useful eventually. Very low poly modeling doesn't mean much anymore nowadays. But knowing how to optimize virtual worlds, however complex they'll become, will always be a good exercise.