You can register for each off their calendar:
They’re offering 4 tours (this is down from 16 a couple of years ago) so if you’re interested, sign up fast. Dates: Tuesday, September 17, Thursday, September 19, Monday September 23 and Thursday, September 26.
They’re also hosting an open house on October 3. Difference is that tours are guided by students, after a presentation by admin in the auditorium, through a mostly empty building. The open house has reps (students and teachers) from each major and you wander the building yourselves, checking out whatever you want. The tours are nice because you’re not crushed with thousands of people in hallways. On the other hand, hallways at Tech are generally always crushed and the open house will give a far more realistic sense of what it’s like to be in a building with 6000 kids.
I’m a 2 time Tech mom and former PTA president so I know this school better than most and will share more later.