For those starting to build on Drupal 8, some things can be in the same place as Drupal 7 while others can be "hidden". While the idea is to move things to more logical places, sometimes it's confusing to site builders since they have to learn the system anew in some regards.
One thing I couldn't find for a bit while working on a new Drupal 8 project was the default search block of all things! The cool system blocks are no longer clumped at the bottom of the block layout page. Instead, for each region there's a "Place block" button. When you click it, all the old blocks and some new friends are available. Cool! See the image for what that modal looks like.