IEEE Spectrum:

The inconvenient truth of future 5G networks is that their increased high-speed bandwidth, and the use of the millimeter wave spectrum (the radio spectrum above 30 gigahertz) to achieve it, comes at a price: Those radio signals barely propagate around the corners of buildings.

In other words, you need a lot more hardware to distribute that sweet, sweet high speed 5G around cities. But that extra hardware means lots of construction, clutter, traffic disruptions and ugly antennas hanging everywhere.

What to do? Someone came up with the idea of turning manhole covers into 5G antennas.

Clever.