מגדל אסתר, Observation tower in Jerusalem, Israel.

Ester is a 16-metre wooden observation tower in the Israeli Jerusalem, standing in the garden of the former Hansen House leprosarium. It was designed by the studio of architect Martin Rajniš and built in Czechia, and its shape was inspired by a flowering cactus. It opened on 10 November 2017 and is the only lookout tower in the city.

The tower was designed by Czech architect Martin Rajniš and represents a recent development in Jerusalem's architectural landscape. The project emerged as part of contemporary efforts to integrate sustainable and organic design principles into the city.

The tower's name, Ester, evokes the biblical queen, but the sources tie the project to Czech-Israeli relations: it was the largest cultural event since the two countries restored diplomatic relations in 1990. Half of the funding came from individuals and companies supporting those ties, alongside contributions from both states and the artist.

Ester stands in the garden of the former Hansen House leprosarium in Jerusalem, and it is the city's only lookout tower. The wooden structure is 16 metres tall, so reaching the viewing level means climbing; the tower was opened on 10 November 2017.

The tower's shape was inspired by a flowering cactus, and it stands in the garden of the former Hansen House leprosarium. It is the only observation tower in the city. Half of the funding came from individuals and companies supporting Czech-Israeli relations.