The new county was a success from the start and growth by the end of the century dictated a wholly new building which was provided in the Classical Revival style by New York architects W.S. Ackerman and Albert Randolph Ross in 1905. The new courthouse was dominated by a quartet of massive Corinthian columns on the outside and an impressive rotunda within. But even this grand new building could not keep up with Union County. By 1925 a seven-floor annex was added and in 1931 a 17-floor tower was tacked on at the cost of $1.2 million.
Decorating the grounds of the Union County Courthouse are a memorial to city firefighters and a cannon, cast in Strasburg in 1758, that was presented by General George Washington to troops from Elizabethtown for their service in their capture of the British position at Stony Point on the Hudson River in 1779.