Terezín is a town in the Czech Republic with around 3,000 inhabitants. It is mainly known for its fortress, and for the Theresienstadt concentration camp; see Holocaust remembrance.
Take the D8 highway, get off at exit 35 or 45. There are multiple parking spots, biggest ones (but there is no shortage of parking space usually) are and of the city.
By busYou can go from Prague, from the Nádraží Holešovice bus station. It takes about 1 hour and takes you to the at the "Terezin U památníku" bus stop. To avoid full bus, you can buy the tickets beforehand at the main bus office on metro station or online.
By trainIt takes 1.5h to Bohušovice nad Ohří , which is 4 km away (approx. 45 minutes by foot).
You can also come from Litoměřice - it's approx. 4 km away too.
The city is small enough to visit it by foot. But bring at least some refreshments - as there will be plenty of walking if you visit at least the areas listed here.
The main "attraction" here is the concentration camp area, which consists of several places:
Ghetto museumPlaced in the building of a former school, it contains an extensive exhibition about the purpose and life in the ghetto - including cinematic artefacts. Expect at least 2-3 hours, if you will study the details. You will learn here about the life and death in the camp, the destinies of people coming in and out, and also about propaganda movies which were shot here to show the camps as a "good and safe place for living" for the imprisoned people.
Small fortressA military citadel, which was used as a political prison during WW2 and as an internment camp for Germans after the war. The exhibition here is mainly devoted to the political prison aspect.
National cemeteryA cemetery mostly with victims from the fortress, approx. 10 000 in total. Of them 2 386 are named, rest are in mass graves. Both Christian cross and Jewish star are here. Many more 10s of thousands people who died here don't have any grave, because they were cremated and the ash dumped into the Ohře river.
Jewish cemetery and crematoryA relatively big remembrance area, with information about the crematory operation - including interior access, which is quite an unsettling experience. Approx. 9 000 people are buried here (mostly Jewish).
The whole city, being a former fortress from year 1780, is surrounded by a star-shaped wall.
Golf KotlinaA modern golf course with a restaurant (both closed in winter).
Multiple restaurants (local cuisine and pizza) and cafés are located , around the "Smetanovy sady" park. The food is not nearly top-notch, but acceptable for the price.
Lidice is a city completely destroyed by the Nazis, as a retaliation for assassination of Heydrich, with a remembrance area in place now - if you still feel like it after Terezin (very unlikely).