Haven't they yet nuked the estates off Pentonville Road from orbit and rebranded King's Cross as Regent's Quarter? I think that's the plan...
Anyway, turn right out of King's Cross / St Pancras and wander along Euston Road. This will ensure you get a good, healthy dose of fumes. But also you'll stumble across the British Library and, a bit further along, the Wellcome Collection (both have good exhibitions - the Wellcome Collection is very good if you have sciency-medical interests).