There are very many things that we would not have if it was not for the Romans:
Towns:
London
Any town with 'Chester' or 'cester' in it's name is probably Roman.
York
Bath
and hundreds more.
Archaeology
This web site!
Rabbits
The months of the year
365 days in a year
Leap years
Straight roads
Laws
Cement
Glass
Bricks
Hadrians Wall
Lots of plants including: