Short answers, pulled from the story.
Tranquility Base is located in the southwestern corner of Mare Tranquillitatis, the Sea of Tranquility, a dark volcanic plain on the Moon's Earth-facing side. It sits near the lunar equator, within five degrees north or south and forty-five degrees east or west of the center of the Moon's facing side.
Apollo 11 landed at Tranquility Base on the 20th of July 1969, at approximately 20:17:40 UTC. Neil Armstrong and Buzz Aldrin lifted off from the surface on the 21st of July at 17:54 UTC.
Armstrong and Aldrin spent two hours and thirty-one minutes on the lunar surface at Tranquility Base. Armstrong stepped out six hours and thirty-nine minutes after landing; Aldrin followed nineteen minutes later.
Roughly one hundred artificial objects remain at Tranquility Base, including the descent stage of the Lunar Module Eagle, a laser reflector, a seismometer, a disc of goodwill messages, and Buzz Aldrin's boots. The US flag planted during the moonwalk was blown over by the ascent rocket exhaust and also remains on the surface.
Neil Armstrong and Buzz Aldrin chose the name just before the mission and told only Capsule Communicator Charles Duke so he would not be caught off guard. Armstrong announced the name at 20:17:58 UTC, approximately eighteen seconds after landing, with the words "Houston, Tranquility Base here. The Eagle has landed." The International Astronomical Union officially recognized the designation, listing it on lunar maps as Statio Tranquillitatis.
California and New Mexico have registered Tranquility Base in their state heritage registers. The US National Park Service, Texas, and UNESCO have each declined to grant it formal status, citing jurisdictional constraints and the Outer Space Treaty. In 2020, the One Small Step to Protect Human Heritage in Space Act was enacted, protecting Tranquility Base and other Apollo landing sites from damage caused by US-licensed space activity.