Uber recently revealed that it would like to make its UberAIR service available to passengers by 2028.

There's already a prototype for the futuristic taxi itself, but another major challenge will be finding a way to support a system of flying taxis that deliver passengers. The solution will involve what UberAIR refers to as "Skyports," or structures for take-off and landing, where passengers can be picked up and dropped off.

On day two of Elevate 2018, Uber's second annual conference for urban air transportation, six architect and design teams showed off their finalist Skyport proposals, which were created based on a few requirements. Each Skyport design had to be able to handle more than 4,000 passengers an hour and stay within a three-acre area — a little under one and a half football fields.

Here's what the Skyport designs looked like: