Rather than a single server, this is a suite: several specialised MCP servers that an assistant coordinates to produce travel itineraries, find flights and accommodation, and surface local events and attractions.
Python, MIT licensed, and among the better adopted independent travel projects catalogued here. The architectural idea is the interesting part: composing narrow servers under an orchestrating assistant, instead of one server that tries to do everything. If you are designing your own travel agent stack, this is worth reading for the structure alone.