When did NYC abandon those sometimes risky third rails for surface streets?

[There are no third rails. What you see are slots for the cars to access an underground electrical conduit. -tterrace]

I'm sure I'll feel foolish as soon as someone fills me in, but I'm not able to figure out what that huge, multistoried, white building directly in front of the Singer building might be. Anyone?

[The City Investing Building, 1908-1968. -tterrace]

Thanks tterrace. What a pile of rubble when they brought that one down. Wow.

What is the building with two Ottoman-inspired cupolas on tops? It's in both photos. It obviously must have been upgraded. 1910 electrical, plumbing and heating are not particularly adapted for 2012 use, so how well did the retrofitting work?

[The Park Row Building. -tterrace]

The 5 story stone building on the left with the mansard dome on roof is not here today. It was razed over 70 years ago. A truly magnificent structure, destroyed to make more open space in NY City as part of the 1939 World's Fair effort. How many million man-hours went into the construction and tear down? It's mind boggling.

[More about the City Hall Post Office and Courthouse here. - tterrace]

This view affords an excellent example of streetcar service from over one hundred years ago. There are at least 16 trolleys visible in this photo, and they are generally evenly spaced as far as you can see. Most other vehicles are horse drawn, with the odd automobile thrown in. The track area is mostly clear, and ridership is probably heavy based on the pedestrian volumes. Present day New Yorkers are still heavy transit users, although most ride the subways and buses today. But any busy city can experience a gap in the bus service, and then they arrive like bananas - in a bunch.

This is a spectacular view - all that's missing is Cass Gilbert's Woolworth Building, which will not be under construction until 1911, on the Broadway block directly opposite the Post Office. In another five years the Mail & Express Building (with the Evening Mail sign) and the old Western Union Building directly behind it will be replaced by Welles Bosworth's AT&T Building. Then the picture will be complete!