Black cells may not touch the border orthogonally and they may not touch each other orthogonally.
The numbers on every domino represent two skyscrapers. The digits outside the grid are the number of skyscrapers that can be seen from that vintage point. A skyscraper is hidden by a higher skyscraper or a skyscraper of equal height. Black cells can be ignored; they have no height.
Solve online in Penpa+ (thx Nick Smirnov!)
Solution code: The digits and black cells in columns A and B, followed by rows C and D. 'S' for a black cell.
on 12. November 2022, 07:14 by Richard
Added link and tag for online solving. Thx Nick!
on 6. November 2022, 04:09 by Nick Smirnov
Penpa:
https://tinyurl.com/28hk4yf5
on 22. November 2014, 09:51 by r45
Echt schwer, aber auch sehr schön mit tollen Schlussweisen. Prima!
on 1. July 2012, 18:31 by sandmoppe
Here's the echo: Very, very wonderful!!!
I've needed several tries and everytime I've learned something new. It was so fascinating, that I couldn't stop trying to solve it.
on 24. June 2012, 00:11 by pin7guin
Ein großartiges Rätsel! Es geht immer Stückchen für Stückchen vorwärts.
on 15. June 2012, 08:16 by Statistica
Großartiges und schwieriges Rätsel. Habe sehr lange gebraucht. Hatte aber auch immer das Gefühl, dass ich ein entscheidendes Argument nicht sehe...?
on 8. June 2012, 18:44 by Richard
Do I hear an echo somewhere? :-))))
on 8. June 2012, 17:23 by MiR
(gestrichen)
on 8. June 2012, 16:44 by Alex
really nicely thought through and constructed