You could use the past tense of sneak, slink, crawl, or slide: they snuck/slunk/crawled/slid stealthily into the city.
Note also that you should not have both "it was very late" and "at midnight", since if you know it was at midnight, that already tells you how late it was.
Midnight City was created in 2010.
Midnight train to Georgia In the midnight hour
Any city found above the Arctic circle can be referred to as the Land of the Midnight Sun.
City Detective - 1953 Cargo of the Midnight - 1.28 was released on: USA: 1954
City Detective - 1953 Cargo of the Midnight 1-28 was released on: USA: 1954
The cast of Midnight City - 2012 includes: Lucinda Farrelle as Maxine "Bunny" Vance Alex Rendall as John
South City Midnight Lady - Doobie Brothers
City Detective - 1953 Midnight Auto Supply 1-26 was released on: USA: 1954
City Detective - 1953 Midnight Supper 2-4 was released on: USA: 9 November 1954
forever chic
Midnight City by M83
M83- Midnight city