Summertide (1990) is a science fiction novel by American writer Charles Sheffield, the first of his series of Heritage Universe. The story takes place millennia in the future, with humans having extensively colonized our spiral arm of the Milky Way and having encountered a number of intelligent alien races. Littered throughout the galaxy are hundreds of massive abandoned engineering projects built by a mysterious race, referred to as The Builders, extinct for three million years. An eclectic group of scientists and opportunists are descending upon one such artifact at a time when its surrounding environment is extremely dangerous to study an unusual phenomenon. The novel includes excerpts from the Lang Universal Artifact Catalog (Fourth Edition), describing several Builder artifacts. Divergence is the next book in the series. Source: Wikipedia (en)