My prefix will quench my thirst

Question

My first 'Riley riddle':

My prefix will quench my thirst,
my suffix is fundamentally measured,
my infix is an ancient capital that is treasured.

What am I?

Answer 1

Very similar to Kevorobin's answer but I think it might actually be

Barometer

My prefix will quench my thirst,

Bar

my suffix is fundamentally measured,

Meter

my infix is an ancient capital that is treasured.

Rome

Answer 2

You are

Hydrometer

My prefix will quench my thirst,

Hydro = Water

my suffix is fundamentally measured,

Meter = A fundamental measurement unit

my infix is an ancient capital that is treasured.

Rome = Italy’s capital and used to be a part of an ancient Roman empire.