Complex sentence: The hotel would be named after the Conti family till 1776 when it was sold to the "comte de Briene" the Dowager Princess dying in the previous year; it was from him that the present building takes its name.
Split into simpler sentences: The hotel would be named after the Conti family till 1776, following death of the Dowager Princess in the previous year, when it was sold to the "Comte de Briene". It was from him that the present building takes its name.