I've never attempted a time lapse in a crowded city, where do I mount myself so I'm not in the way?
There are probably as many solutions to this as there are locations in cities
A brief selection...
Indoors. Shoot through a window.
As noted in comments, this could include a parked car, though there are potential vibration issues.
Lash the camera to a lamp-post, tree, pillar, fence, etc - though again beware of transmitted vibration.
Elevate yourself - A stairway which isn't currently in use - a bank on a Sunday etc. or a statue plinth might be just sufficiently out of the way that people aren't constantly pushing past you.
Immediately inside any cordoned-off area. Looking out from a nearby park or small green space. Though the park may be busy behind you & the street in front, no-one is going to need to be right by the fence.
Brave it out. Make your own cordon with cones & tape... this is likely to raise the interest of the local constabulary, so get a permit.