Every major north american city has a legacy telco central office in downtown, in a very central location, from the days of pulse-dial and then DTMF dial analog phones. Always owned by whatever corporate entity the Bell System and then ILEC eventually became.

Seattle, for example, also has the Elliot CO in Belltown: http://www.co-buildings.com/wa/206/

Yeah, you have to remember that in pulse dial days a central office station had a reach of roughly 3 miles. The longer you go, the more you're paying for cable, repeaters, or just losing quality. 90 volt AC for ringing has a limited range!

People who've never seen it in person find it amazing that things like 1200 pair phone cables exist... Here's a photo of just a 100-pair:

https://imgur.com/gallery/f1EGp

on this page is a photo of a 1200-pair: http://cityinfrastructure.com/single.php?d=RuralOutsidePlant...

How do they colour-code the wires to identify them?

"Ah there's your problem: you've patched the Fire Engine Red pair, it's meant to be the Ferrari Red. Rookie error."

> How do they colour-code the wires to identify them?

It’s actually pretty simple. There are only 10 colors: blue, orange, green, brown, slate, white, red, black, yellow, and violet. They’re grouped in “binders” (using colored strings). You’re likely familiar with the first four pairs from network cables (which omit the white/slate pair). After cylcling through blue through slate paired with white through violet (25 pairs), the wires are bundled with binders starting with blue/white string. That gets you to 625 pairs (the first picture posted above is 600 or 625 pairs). After that, the binder groups are bound in a similar fashion (typically if you’re going beyond 625, the slate/violet binder is omitted to get a nice round 600 in the first group).

Wikipedia has a good article: https://en.m.wikipedia.org/wiki/25-pair_color_code

100-pair cable is only about 3/4” diameter. I have a 24-line 1A2 telephone that uses 75 pairs just to connect to the phone switch and two 100-pair cables feeding a telephone display case in my living room.

It takes me about a half hour to punch down 100 pairs on a 66-block. Old school telecom guys could probably do it in under 10 minutes.

What about if you are color blind? Change professions?

Yes. Same problem for fiber fusion splicers. Worked for an ISP that hired a color blind person as a field tech, he didn't last long.

I'm pretty sure we have Human Rights Conventions to protect people from having to crimp a mess like that.

At least I hope so, if not, then they really should exist.

Once I learned to recognize what an telephone exchange looks like, I have a hard time not seeing them. All over the place. Downtown, neighborhoods, etc. Big, unmarked buildings with no windows, mostly concrete, lots of infrastructure on top, and various telco trucks parked around at all hours.

They look surprisingly similar to electricity substations, with the key differences being style (substations are usually older) and the vehicles parked in front.

Fiber hotels are in all the big cities, Westin Building Exchange on 5th Ave in Seattle is where a ton of peering also happens.

3rd Ave wouldn't be my first choice to locate a new ISP store, or any new retail location. 4th or 5th would be better. Going up the hill to somewhere like Boren and Madison might be easier for people across the city to reach.

The historic reasons from other posters give good justification for the current location.