Here's an absolutely gorgeous Doom map called Lullaby

Lullaby is a sprawling, beautiful map for Doom 2 that puts the level and visual design of many full-fledged, expensive games to shame. Created by mapper-modder Danlex for Doom port GZDoom, it's a testament to the game design talents that lay deep in the communities of modders and mappers for old games.

Lullaby is kind of insane from a technical standpoint pic.twitter.com/nlLFCmQle5February 16, 2021

Lullaby does shocking things if you know the constraints of the original Doom engine, and it does them well. It's a very technically focused creation, with a lot of emphasis put on how it looks, the aesthetic, sense of place, and surreal, dream-like nature of the environment. It's not too ultra-hard, even, so if you want to go at it as a Doom novice that's perfectly fine. It takes about an hour to play through.

You can find the map on the Doomworld forums, and modder Danlex on Twitter.