Visiting NYC w/twins - ??

coffee bean

Hi NYC Moms!  I am thinking about going to visit a friend in Brooklyn in December w/my 7-month old twins.  I'd have someone w/me to help get around (she'd in a 4th floor walkup!), but I was wondering how on earth you get around with two babies in NYC? 

I know we'll want to go into Manhattan - Is it safe to take a cab?  Do you just hold the baby(ies)?  What about the subway?  I know I've seen parents bringing strollers up and down the steps to the subway, but can't recall ever seeing twin infants / strollers on the subway.

I lived in NYC for 2 yrs, so I'm pretty familiar with the area and want to give it a try - if it's a good idea!