Hello, 

If your rank is in top 500 then you can easily get an architecture seat in top NITs. like SPA Delhi,NIT Trichy

The cutoff for B.Arch courses is about 50% of the total marks.

Above 70% and you can get a seat in one of the finest institutions in India offering B.Arch.

For B.Arch at IITs the admission is based on JEE Advanced Rank and for admission in NITs, SPA, BIT Mesra, SMVDU the admission is based on JEE Main Paper 2 Rank.

The Opening rank for SPA New Delhi was 98 and it closed at 798. For candidates that did not have any state quota the closing rank was 827 in NIT Tiruchirappalli and 2377 in NIT Patna.

Basically if you want to get in any nit , you have to be under 2.5k rank.

Here is the list of colleges accepting nata score with cutoff marks.Go through the link.

https://collegedunia.com/news/e-271-nata-2015-cutoff