In downtown Des Moines, chances are that construction of a big project means the demolition of a project that was new decades ago. In that vein, crews began demolishing the former Allied Insurance building at Fifth Avenue and Park Street today to clear the site for the construction of the $101 million Iowa Events Center Hotel. The former Allied building has been vacant for several years, though it did provide short-term office space for American Enterprise Group Inc. during that company’s $35 million renovation of its historic headquarters at 601 Sixth Ave. Construction of the 330-room convention center hotel is scheduled to begin in March, with an opening anticipated two years later in March 2018. After viewing conceptual drawings of the interior of the Hilton-branded hotel, its nonprofit operating board was told that about $2 million in projected cost overruns have been eliminated in the past month, bringing the current overrun to $3 million. The board was told that anything that amounts to more form than function will be eliminated to meet the budget.