Logic Masters Deutschland e.V.

This puzzle is largely thanks to the overwhelming feedback on my first Double Trouble Skyscraper puzzle.
I wanted to construct a puzzle that combines the element of buildings with doubled height with the element that the cells with these buildings are not given, but have to be determined by the solver. I thought about a suitable ruleset for a long time until I finally found one that works well and is elegant and quite simple at the same time.
I had to get out of my comfort zone to construct this puzzle. So I'm all the happier with the result, which is definitely one of the best puzzles in my Double Trouble series.

As always, I have linked the various other puzzles in the series below the picture.

Rules:

Sudoku: Fill every row, column and 3x3 box with the digits 1-9.

Skyscraper: Each cell in the grid represents either a normal building (height = digit in the cell) or a important building (height = twice the digit in the cell). A clue outside the grid gives the number of buildings that are visible in the corresponding row or column looking from that direction. A building is visible if it's higher than all buildings in front of it.

Downtown Dilemma: The cells with important buildings has to be determined by the solver using the following rules:
Important buildings cannot touch each other not even diagonally.
A digit in a cell with a circle gives the number of important buildings in the row and column crossing in the circled cell including the circled cell itself.
All possible circles are given (negative constraint).

Have fun solving!

Sudoku on:
f-puzzles
CTC-App

The Double Trouble series:
In this series I show puzzles in which, for some cells, the double value of the digit for is considered for the rule variant(s).
The following puzzles have been published so far and show a great variety, with something for everyone.

Doubletime (Difficulty: 1/5, Killer, Easy start in the series)
Double Trouble - Thermo (Difficulty: 2/5, Thermo)
Double Trouble - Arrows (Difficulty: 2/5, Arrow)
Double Trouble - XV (Difficulty: 2/5, extended XV)
Double Trouble - Killer (Difficulty: 3/5, Killer)
Double Trouble - Skyscraper (Difficulty: 3/5, Skyscraper)
The Diamonds Will Do It (Difficulty: 3/5, Arrow, Double Trouble cells as symmetry breaker) needs a rating
Wrecking Ball (Difficulty: 4/5, Killer, shows a trick with Double Trouble cells) needs a rating
Double Trouble Celebration (Difficulty: 4/5, Mash-up of all 5 variants, a lot of interesting interaction) needs a rating
The Key (Difficulty: 4/5, Equalines) needs a rating
Hyperloop (Difficulty: 4/5, Killer, Loop made from Double Trouble cells) needs a rating
Doubles Hidden Inside Squares (Difficulty: 4/5, Killer, Hidden Double Trouble cells) needs a rating

I look forward to any feedback and suggestions about the series.