Hilary Duff and her husband, Mike Comrie, stepped out in NYC with their son, Luca, yesterday. The family of three has been exploring the Big Apple since arriving last week. Mike and Hilary went for a walk with Luca on Thursday as they enjoyed the hot Summer weather. Little Luca, who is just 4 months old, is already becoming quite the traveler with recent visits to Mexico and Napa. Hilary's been sharing plenty of snaps of Luca during their many adventures, since she's currently working with Nikon on its Small Moments Are Huge campaign.