My link is over 1 Km distance.
my recommendation is still get a couple of Ubnt boxes with directional antennas if you have line of sight. If you boost to 2watt and you are allowed only .1 watt you WILL get into trouble if just one of your neighbours have any Wifi knowledge.
And remember the 100mw is from ANTENNA out - not what the box is set for. So if you use a high gain antenna plus amplifier plus short antenna cables - your real output might end up in the 3-4 watt range.
And.. remember the LOWER the Frequency the better "wall penetration" you will get. 5GHz have very little through wall penetration where 2.4GHz is better and 900 Mhz is even better. :-) If the 900MHz frequencies are allowed in Greece that was what I would do for a 1km link. On top of that you will have to experiment with ACP settings to optimize them to a 1KM link.
If you want to get the best speed - then back to my original suggestion. They RocketMGPS from UBNT. They use GPS to set the ACK settings to get a "true" TDMA signal (Time Division - so each device knows when it can transmit and they don't try to talk at the same time) 1KM links without TDMA will get issues from time to time due to ACK settings. Home wifi routers are not made for more than about 150feet so their AutoACK algorithms will quite often NOT work well on longer distance.
High speed "bridge"
http://ubnt.com/rocketmgpsMost of the UBNT products are outdoor and "damn" cheap compared to the competition. The rocket without GPS have some TDMA but not perfect like the GPS version.
Alternative is MikroTik routers with their NV wireless. Cheaper but requires the big Mikrotik Book of Mumbo Jumbo to get working :-)