Synergy Photoworks said
waist.it
Thanks - noted!
Unfortunately, the floors are also reinforced concrete :(
Damn!
In which case I fear you will probably need to run cables to key nodes, each node with a small Ethernet switch and/or a WAP for connections within that particular room. We had to do similar with my in-laws' place in Hungary back in the mid noughties. He actually built the house in the late 1950s. Made rather a good job of it too - all steel-reinforced concrete including all floors/ceilings. It even had a bomb-resistant basement - a legal planning requirement at the time he built it, apparently. :-)
This meant that Wi-Fi through the walls and ceilings, even from a WAP in an adjacent room was hopeless. Even FM radios had to be placed near a window! So it meant running Cat5e cables through incredibly hard, thick concrete walls. Destroyed several 8mm SDS drill bits and nearly burnt out his new Bosch SDS drill too. But we got there in the end, creating quite a fast and robust system that is still in use today. Though if I were doing it today I'd use Cat6 rather than Cat5e Ethernet cable.
Unfortunately, I really don't think that in your situation there are any practical shortcuts, except possibly one: study your building and plan your cable routes carefully! Perhaps even draw a sketch plan for yourself. I know from first-hand experience that can significantly reduce the amount of sweat required to complete the job.
For example it might be better to run some of the cables outside in armoured Cat6. You might also be able to use existing holes and/or ducts, such as those used for pipework. You might be able to serve Wi-Fi to an opposite room by positioning a WAP so it can transmit through two doorways that happen to line-up nicely - thus serving two rooms instead of jut one. You might even be able to serve the entire side of the building by placing a weather resistant WAP up a pole a few metres from the property, effectively squirting Wi-Fi signal through the windows. That kind of thing... :-)
I'd add that having Ethernet in key locations regardless of your Wi-Fi provision is probably a good idea anyway. I wired key nodes shortly after we moved into our place back in 2012. Whilst having the big single "whole house" WAP in the roof is excellent, I prefer to use it for devices that cannot connect any other way. Consequently, our media and backup servers, security cams, weather station transponder etc, as well as the laptop I'm using right now to communicate/maintain various remote servers, are still all connected over Ethernet rather than Wi-Fi.
In any event when you do finally bite the proverbial bullet, I would genuinely be interested to know what you finally decide to do, and how well it works out for you. :-)