The electron-positron Future Circular Collider at CERN presents a unique physics reach, covering from the exploration of the Higgs boson properties, to BSM searches, to flavour physics and to precision electroweak measurements.

Realizing the full physics potential of FCCee will require the design of new, challenging particle physics detectors. Excellent tracking, high energy resolution and particle identification capabilities are required, along with precise control over systematics.
As an example of this new generation of these future experiments I will present the ALLEGRO detector concept. Built around a novel design of a noble liquid electromagnetic calorimeter, it aims to fulfill all these challenges.
The concept and its design principles will be presented, along with the options considered for its subdetectors.