Title: What every student of math or cs should know about Euclidean constructions Abstract: Historically, the first extensive family of algorithms was Euclid's constructions with ruler and compass. Also the first (and still the most famous) impossibility results in mathematics (like "squaring the circle") were connected with Euclidean constructions. In this talk we shall review what should have been taught (and once upon a time was indeed taught) in high school about this topic. We shall also discuss it from the following five modern perspectives: 1) The logical content and complexity of Euclidean "construction problems" 2) Euclidean constructions as constructive existence proofs 3) Euclidean constructions as algorithms/programs 4) Euclidean constructions from an algebraic point of view 5) Euclidean constructions and the axioms of Euclidean Geometry